Patent Publication Number: US-2022230009-A1

Title: Fingerprint recognition module, display panel and driving method, and display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of Chinese patent application No. 202110079487.7, filed on Jan. 21, 2021, the entirety of which is incorporated herein by reference. 
     FIELD 
     The present disclosure generally relates to the field of display technology and, more particularly, relates to a fingerprint recognition module, a display panel and driving method, and a display device. 
     BACKGROUND 
     With the development of technology, a variety of display devices with fingerprint recognition function have appeared on the market, such as a mobile phone, a tablet computer, and a smart wearable device. Because fingerprints are inherent and unique to individuals, the use of fingerprint recognition function is capable of improving the safety factor of the display device. Before operating the display device with a fingerprint recognition function, authorization verification may be performed by touching the display device with a finger, which simplifies the authorization verification process. Fingerprint recognition technology may often be divided into optical fingerprint recognition technology, silicon-chip fingerprint recognition technology, and ultrasonic fingerprint recognition technology. 
     Currently, ultrasonic fingerprint recognition technology is a popular research direction for major manufacturers. In ultrasonic under-screen fingerprint recognition technology, a high-voltage is often used to drive a piezoelectric film layer to form ultrasonic waves. To obtain sufficient fingerprint signals, strong ultrasonic waves are needed, and the driving voltage often reaches approximately 100 V. However, a large-area ultrasonic fingerprint recognition unit in the display screen easily causes a large capacitance in the entire driving loop and a substantially high power loss during the driving process. For example, for an ultrasonic fingerprint recognition unit with an area of approximately 1 cm 2 , the parasitic capacitance may reach 1 nF, and the peak current can reach 6 A driven by a peak voltage of 100 V with 10 MHz frequency. For a driving loop resistance of 1 ohm, the power can reach as high as 18 W. 
     Therefore, how to provide a fingerprint recognition module, a display panel and driving method, and a display device that is capable of reducing power consumption, achieving ultrasonic fingerprint recognition, and improving recognition performance is an urgent problem that needs to be solved. 
     SUMMARY 
     One aspect of the present disclosure provides a fingerprint recognition module. The fingerprint recognition module includes a first electrode layer including a plurality of first electrodes that are arranged in an array, and a piezoelectric layer disposed on a side of the first electrode layer. The fingerprint recognition module also includes a second electrode layer disposed on a side of the piezoelectric layer facing away from the first electrode layer. The second electrode layer includes a plurality of second electrodes that are arranged along a first direction, and one second electrode of the plurality of second electrodes overlaps at least two first electrodes of the plurality of first electrodes. Moreover, the fingerprint recognition module includes a flexible circuit board bonded and connected to the plurality of second electrodes. In a plane parallel to the first electrode layer, the plurality of second electrodes and the flexible circuit board are arranged along a second direction, and the first direction intersects the second direction. 
     Another aspect of the present disclosure provides a display panel. The display panel includes a fingerprint recognition module. The fingerprint recognition module includes a first electrode layer including a plurality of first electrodes that are arranged in an array, and a piezoelectric layer disposed on a side of the first electrode layer. The fingerprint recognition module also includes a second electrode layer disposed on a side of the piezoelectric layer facing away from the first electrode layer. The second electrode layer includes a plurality of second electrodes that are arranged along a first direction, and one second electrode of the plurality of second electrodes overlaps at least two first electrodes of the plurality of first electrodes. Moreover, the fingerprint recognition module includes a flexible circuit board bonded and connected to the plurality of second electrodes. In a plane parallel to the first electrode layer, the plurality of second electrodes and the flexible circuit board are arranged along a second direction, and the first direction intersects the second direction. 
     Another aspect of the present disclosure provides a driving method of a display panel. The driving method is configured to drive the display panel to perform a touch detection and a fingerprint recognition. The driving method includes providing the display panel. The display panel includes a fingerprint recognition module and a touch-control layer. The fingerprint recognition module includes a first electrode layer including a plurality of first electrodes, a piezoelectric layer disposed on a side of the first electrode layer, and a second electrode layer disposed on a side of the piezoelectric layer facing away from the first electrode layer. The second electrode layer includes a plurality of second electrodes. The fingerprint recognition module also includes a flexible circuit board bonded and connected to the plurality of second electrodes, and a driving circuit layer electrically connected to the first electrode layer. The driving circuit layer includes a plurality of driving circuits, a common signal line, a scanning line, a detection signal line, a power signal line, and a sampling signal line, and a driving circuit of the plurality of driving circuits includes a first transistor, a second transistor, a third transistor, and a storage capacitor. The driving method also includes determining a touch position of a finger through the touch-control layer, for the touch detection; and determining a second electrode of the plurality of second electrodes corresponding to the touch position of the finger. Moreover, the driving method includes providing an excitation signal only to the second electrode corresponding to the touch position of the finger. A corresponding first electrode of the plurality of first electrodes is connected to a common potential, and the piezoelectric layer between the second electrode and the first electrode corresponding to the touch position of the finger generates ultrasonic waves. Further, the driving method includes performing, by the driving circuit corresponding to the second electrode corresponding to the touch position of the finger, ultrasonic fingerprint recognition, for the fingerprint recognition. 
     Other aspects of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To more clearly illustrate the embodiments of the present disclosure, the drawings will be briefly described below. The drawings in the following description are certain embodiments of the present disclosure, and other drawings may be obtained by a person of ordinary skill in the art in view of the drawings provided without creative efforts. 
         FIG. 1  illustrates a schematic top-view of an exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 2  illustrates a schematic B-B′ sectional view of an exemplary fingerprint recognition module in  FIG. 1  consistent with disclosed embodiments of the present disclosure; 
         FIG. 3  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 4  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 5  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 6  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 7  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 8  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 9  illustrates a schematic C-C′ sectional view of an exemplary fingerprint recognition module in  FIG. 8  consistent with disclosed embodiments of the present disclosure; 
         FIG. 10  illustrates a schematic D-D′ sectional view of an exemplary fingerprint recognition module in  FIG. 7  consistent with disclosed embodiments of the present disclosure; 
         FIG. 11  illustrates a schematic C-C′ sectional view of another exemplary fingerprint recognition module in  FIG. 8  consistent with disclosed embodiments of the present disclosure; 
         FIG. 12  illustrates a schematic top-view of another exemplary fingerprint recognition module consistent with disclosed embodiments of the present disclosure; 
         FIG. 13  illustrates a schematic E-E′ sectional view of an exemplary fingerprint recognition module in  FIG. 12  consistent with disclosed embodiments of the present disclosure; 
         FIG. 14  illustrates a schematic diagram of an equivalent circuit connection of a plurality of driving circuits of an exemplary driving circuit layer consistent with disclosed embodiments of the present disclosure; 
         FIG. 15  illustrates a schematic diagram of a connection of a driving circuit in  FIG. 14  consistent with disclosed embodiments of the present disclosure; 
         FIG. 16  illustrates an operating timing diagram of a driving circuit consistent with disclosed embodiments of the present disclosure; 
         FIG. 17  illustrates a schematic diagram of an exemplary display panel consistent with disclosed embodiments of the present disclosure; 
         FIG. 18  illustrates a F-F′ cross-sectional view of an exemplary display panel in  FIG. 17  consistent with disclosed embodiments of the present disclosure; 
         FIG. 19  illustrates a F-F′ cross-sectional view of another exemplary display panel in  FIG. 17  consistent with disclosed embodiments of the present disclosure; 
         FIG. 20  illustrates a schematic flowchart of an exemplary driving method of a display panel consistent with disclosed embodiments of the present disclosure; 
         FIG. 21  illustrates a schematic flowchart of another exemplary driving method of a display panel consistent with disclosed embodiments of the present disclosure; and 
         FIG. 22  illustrates a schematic top-view of an exemplary display device consistent with disclosed embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Reference will now be made in detail to exemplary embodiments of the disclosure, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the alike parts. The described embodiments are some but not all of the embodiments of the present disclosure. Based on the disclosed embodiments, persons of ordinary skill in the art may derive other embodiments consistent with the present disclosure, all of which are within the scope of the present disclosure. 
     The terms used in the disclosed embodiments of the present disclosure are merely for the purpose of describing specific embodiments and are not intended to limit the present disclosure. Similar reference numbers and letters represent similar terms in the following Figures, such that once an item is defined in one Figure, it does not need to be further discussed in subsequent Figures. 
     The present disclosure provides a fingerprint recognition module.  FIG. 1  illustrates a schematic top-view of a fingerprint recognition module consistent with disclosed embodiments of the present disclosure; and  FIG. 2  illustrates a schematic B-B′ sectional view of the fingerprint recognition module in  FIG. 1 . Referring to  FIG. 1  and  FIG. 2 , the fingerprint recognition module  000  may include a first electrode layer  10  including a plurality of first electrodes  101  that are arranged in an array, a piezoelectric layer  20  disposed on a side of the first electrode layer  10 , and a second electrode layer  30  disposed on a side of the piezoelectric layer  20  facing away from the first electrode layer  10 . For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 1  illustrates a transparency filling. The second electrode layer  30  may include a plurality of second electrodes  301  that are arranged along a first direction X. Optionally, adjacent second electrodes  301  may be insulated from each other. One second electrode  301  may overlap at least two first electrodes  101 . 
     In addition, the fingerprint recognition module may also include a flexible circuit board  40  (not filled in  FIG. 1 ) bonded and connected to the second electrodes  301 . In a plane parallel to the first electrode layer  10 , the second electrode  301  and the flexible circuit board  40  may be arranged along a second direction Y. The first direction X may intersect the second direction Y. Optionally, in the plane parallel to the first electrode layer  10 , the first direction X may be perpendicular to the second direction Y. Optionally, referring to  FIG. 2 , the structure of the fingerprint recognition module  000  may be formed over a substrate  00 , and the substrate  00  may be configured to carry the above-mentioned film structures of the fingerprint recognition module  000 . 
     Specifically, the fingerprint recognition module  000  in the present disclosure may be a fingerprint recognition module using ultrasonic technology. The fingerprint recognition module  000  may mainly include three stacked structures of the first electrode layer  10 , the piezoelectric layer  20 , and the second electrode layer  30 . The first electrode layer  10  may include the plurality of first electrodes  101 , and the plurality of first electrodes  101  may be arranged in an array. Optionally, adjacent first electrodes  101  may be insulated from each other. The second electrode layer  30  disposed on the side of the piezoelectric layer  20  facing away from the first electrode layer  10  may include the plurality of second electrodes  301  that are insulated from each other, and the plurality of second electrodes  301  may be arranged along the first direction X. One second electrode  301  may overlap at least two first electrodes  101 . Optionally, the piezoelectric layer  20  may be laid on a surface of the first electrode layer  10  as an entity. The second electrode  301  may be used as a driving electrode (a transmitting terminal), and the first electrode  101  may be used as a receiving electrode (a receiving terminal). 
     When the fingerprint recognition module  000  performs fingerprint recognition, the flexible circuit board  40  may provide an alternating current signal to the second electrode  301 . The driving voltage applied between the first electrode  101  and the second electrode  301  may change constantly, and, thus, the piezoelectric layer  20  may vibrate to generate ultrasonic waves. When performing a touch recognition on a touch-control subject such as a finger, because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. According to the voltage signals that change differently, the positions of the valleys and the ridges of the fingerprint may be determined, the determination result may be fed back to the first electrode  101 , and may be ultimately read and be converted to a fingerprint image by the flexible circuit board  40 , to achieve the fingerprint recognition. 
     In the fingerprint recognition module  000 , the second electrode layer  30  may include a plurality of second electrodes  301  that are insulated from each other. For illustrative purposes,  FIG. 1  illustrates that the second electrode layer may include three second electrodes as an example. The flexible circuit board  40  that provides the driving voltage signal for the fingerprint recognition module  000  and reads the fingerprint detection signal may be directly bonded and connected to the second electrodes  301 . In other words, referring to  FIG. 1  and  FIG. 2 , the second electrodes  301  may be extended to a region where the flexible circuit board  40  is located and may partially overlap the flexible circuit board  40 , thereby achieving the direct binding connection between the flexible circuit board  40  and the second electrodes  301 . 
     In the prior art, the second electrode  301  is often connected to the flexible circuit board  40  through a thin lead to achieve the transmission of an electrical signal. A width of the lead used as a wiring is significantly different from a width of the second electrode  301  used as a driving electrode, and the width of the general lead is much smaller and is a few hundredths or even a few thousandths of the width of the second electrode  301 . According to the calculation formula of resistance: R=ρL/S, where R is resistance, p is resistivity, L is a length of a resistor, and S is a cross-sectional area of the resistor, the size of the line width may affect the size of the cross-sectional area of the resistor, thereby affecting the resistance value of the resistor. The smaller the line width, the smaller the cross-sectional area, and the greater the resistance. Therefore, when the conditions are basically the same, the resistance of the lead used as the wiring may be much greater than the resistance of the second electrode  301  used as the driving electrode. 
     Therefore, in the disclosed embodiments, the flexible circuit board  40  configured to provide the driving voltage signal to the fingerprint recognition module  000  and to read the fingerprint detection signal may be directly bonded and connected to the second electrodes  301 , and the lead may not be used in the module structure, which may effectively avoid the loss of the driving signal transmitted between the flexible circuit board  40  and the second electrode  301  and serious power loss due to large impedance of lead, thereby reducing the power loss of the fingerprint recognition module  000 , achieving ultrasonic fingerprint recognition, and improving recognition performance. 
     In addition, in the disclosed fingerprint recognition module  000 , the plurality of first electrodes  101  of the first electrode layer  10  may be arranged in an array of multiple rows and multiple columns, while the plurality of second electrodes  301  of the second electrode layer  30  may be arranged in an array of one row and multiple columns. In other words, along the second direction Y, there may be merely one row of second electrodes  301 ; and along the first direction X, a plurality of second electrodes  301  may be arranged in sequence. Optionally, one second electrode  301  in the disclosed embodiments may overlap at least two first electrodes  101 . In one embodiment, a quantity of the second electrodes  301  of the second electrode layer  30  may be more than one, and the plurality of second electrodes  301  may be arranged along the first direction X. 
     In the second direction, each second electrode  301  may be directly bonded to the flexible circuit board  40  for electrical connection. Therefore, when performing fingerprint recognition, each second electrode  301  may be driven separately. In other words, when a touch event occurs, the flexible circuit board  40  may merely provide alternating current signal to the second electrode  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at a position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. According to the voltage signals that change differently, the positions of the valleys and the ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs, and may be ultimately read and be converted to a fingerprint image by the flexible circuit board  40 , to achieve the fingerprint recognition. 
     Therefore, in one embodiment, a quantity of the second electrodes  301  of the second electrode layer  30  may be more than one, and the plurality of second electrodes  301  may be arranged along the first direction X. In the second direction, each second electrode  301  may be directly bonded to the flexible circuit board  40  for electrical connection, and the lead may not be used in the module structure, which may effectively avoid the loss of the driving signal transmitted between the flexible circuit board  40  and the second electrode  301  and serious power loss due to large impedance of lead, thereby reducing the power loss of the fingerprint recognition module  000 , achieving ultrasonic fingerprint recognition, and improving recognition performance. Further, when the touch event occurs, the flexible circuit board  40  may merely provide the alternating current signal to the second electrode  301  involved in the touch event, and may not provide the signals to the remaining second electrodes  301 . Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. 
     It should be understood that for illustrative purposes,  FIG. 1  and  FIG. 2  merely illustrate schematic diagrams illustrating the structure of the fingerprint recognition module  000 , and any other structure may also be included, which may not be limited by the present disclosure. Optionally, both the first electrode layer  10  and the second electrode layer  30  may be made of a metal material, and, thus, the first electrode  101  and the second electrode  301  may be made of the metal material. The metal material may not only have desired electrical conductivity, but also have desired bonding connection effect between the second electrodes  301  and the flexible circuit board  40 . In one embodiment, the piezoelectric layer  20  may be made of a piezoelectric material with a substantially high piezoelectric voltage constant, such as polyvinylidene fluoride (PVDF), such that the fingerprint recognition module  000  in the disclosed embodiments may have a substantially high receiving sensitivity to ultrasonic waves, which may facilitate to improve fingerprint recognition performance. 
       FIG. 3  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure. For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 3  illustrates a transparency filling. In certain embodiments, referring to  FIGS. 1-3 , the flexible circuit board  40  may include a plurality of pins  401 , and one second electrode  301  may be bonded and connected to one pin  401 . 
     The disclosed embodiments may explain that the second electrode  301  may be extended all the way to the region where the flexible circuit board  40  is located and may partially overlap the flexible circuit board  40 . For achieving the direct bonding connection between the flexible circuit board  40  and the second electrode  301 , the flexible circuit board  40  may include the plurality of pins  401 , and one second electrode  301  may be bonded and connected to one pin  401  (as shown in  FIG. 3 ), such that the driving signals may be provided to each second electrode  301 , respectively. 
     Optionally, along the first direction X, a ratio of a width W 1  of the pin  401  over a width W 2  of the second electrode  301  may be in a range of approximately 0.9-1.1. In other words, along the first direction X, the width W 1  of the pin  401  may be approximately equal to the width W 2  of the second electrode  301 , which may facilitate the bonding connection between the second electrode  301  and the pin  401  of the flexible circuit board  40  when the second electrode  301  is extended along the second direction Y to the region where the flexible circuit board  40  is located. 
     Optionally, considering the process deviation, along the first direction X, the ratio of the width W 1  of the pin  401  over the width W 2  of the second electrode  301  may be in a range of approximately 0.9-1. In other words, the width W 1  of the pin  401  may be slightly smaller than the width W 2  of the second electrode  301 . 
       FIG. 4  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure. For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 4  illustrates a transparency filling. In certain embodiments, referring to  FIGS. 1-2  and  FIG. 4 , the flexible circuit board  40  may include a plurality of pins  401 , and one second electrode  301  may be bonded and connected to multiple pins  401  of the plurality of pins  401  arranged at intervals. 
     The disclosed embodiments may explain that the second electrode  301  may be extended all the way to the region where the flexible circuit board  40  is located and may partially overlap the flexible circuit board  40 . For achieving the direct bonding connection between the flexible circuit board  40  and the second electrode  301 , the flexible circuit board  40  may include a plurality of pins  401 , and one second electrode  301  may be bonded and connected to the multiple pins  401  arranged at intervals (as shown in  FIG. 4 ). 
     Because in the manufacturing process, a high-temperature process is adopted to achieve the bonding and electrical connection between the second electrode  301  and the pin  401  of the flexible circuit board  40 , the pin  401  may undergo thermal expansion when being subjected to a high temperature. Therefore, through configuring one second electrode  301  to be bonded and connected to the multiple pins  401  arranged at intervals, a buffer space for the thermal expansion of the pin  401  during the manufacturing process may be provided, which may facilitate to improve the bonding effect of each second electrode  301  and the flexible circuit board  40 . 
       FIG. 5  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure. For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 5  illustrates a transparency filling. In certain embodiments, referring to  FIG. 5 , the fingerprint recognition module  000  may include a plurality of second electrodes  301 , and the plurality of second electrodes  301  may be arranged along the first direction X. 
     Each second electrode  301  may be regarded as an entity, and may include a first sub-portion  3011  and a second sub-portion  3012  that are adjacent to each other in the second direction Y. The first sub-portion  3011  may be a portion of the second electrode  302  that is bonded and connected to the flexible circuit board  40 , and the second sub-portion  3012  may be the remaining portion of the second electrode  301 . Along the first direction X, a width W 7  of the second sub-portion  3012  may be greater than a width W 8  of the first sub-portion  3011 . 
     The disclosed embodiments may explain that the fingerprint recognition module  000  may include a plurality of second electrodes  301 , and the plurality of second electrodes  301  may be arranged along the first direction X. When the flexible circuit board  40  includes a plurality of pins  401 , and one second electrode  301  is bonded and connected to one pin  401 , the portion where the second electrode  301  is bonded and connected to the flexible circuit board  40  may be substantially narrow, while the remaining portion may be substantially wide. In other words, each second electrode  301  may be regarded as an entity, and may include the first sub-portion  3011  and the second sub-portion  3012  that are adjacent to each other in the second direction Y. The first sub-portion  3011  may be the portion of the second electrode  302  that is bonded and connected to the flexible circuit board  40 , and the second sub-portion  3012  may be the remaining portion of the second electrode  301 . Along the first direction X, the width W 7  of the second sub-portion  3012  may be greater than the width W 8  of the first sub-portion  3011 . For example, the width W 8  of the first sub-portion  3011  may be ½ or ⅓, etc., of the width W 7  of the second sub-portion  3012 . 
     Therefore, while achieving the direct bonding connection between the second electrode  301  and the pin  401  of the flexible circuit board  40 , the area of the pin  401  of the flexible circuit board  40  may be reduced, which may facilitate to reduce the area of the flexible circuit board  40 , to save the space occupied by the flexible circuit board  40 , and to achieve the miniaturization development of the entire fingerprint recognition module  000 . 
       FIG. 6  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure. For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 6  illustrates a transparency filling. In certain embodiments, referring to  FIG. 6 , the second electrode  301  may have a rectangular shape. Along the first direction X, a length of the second electrode  301  may be A; and along the second direction Y, a length of the second electrode  301  may be B, where B&gt;A. 
     The disclosed embodiments may explain that each of the second electrodes  301  of the second electrode layer  30  arranged in an array of one row and multiple columns may have a rectangular shape. In other words, along the first direction X, the length of the second electrode  301  may be A, and along the second direction Y, the length of the second electrode  301  may be B, where B&gt;A. The second electrode  301  may have a rectangle shape whose length in the second direction Y is greater than the length in the first direction X. Because the fingerprint contact region in the fingerprint recognition technology often has a square shape, in one embodiment, to reduce power loss, each second electrode  301  may be directly extended to the position where the second electrode  301  overlaps the flexible circuit board  40 , and may directly overlap the flexible circuit board  40 . Therefore, through configuring the second electrode  301  to have a rectangular shape, after removing the portion that is bonded to and overlaps the flexible circuit board  40 , the remaining portion of each second electrode  301  may form a square structure as much as possible, which may facilitate to meet the shape and size requirements required for fingerprint recognition. 
     Optionally, referring to  FIG. 6 , the area required to identify fingerprint may often be approximately 25 mm 2 . Therefore, when a touch event occurs, if the touch subject such as a finger is merely located on one second electrode  301 , the length A of the second electrode  301  along the first direction X may be approximately 4 mm-5 mm, and the length B of the second electrode  301  along the second direction Y may be approximately 6 mm-8 mm. The area occupied by the flexible circuit board  40  in the second direction Y may be reduced, which may facilitate to increase the area of fingerprint recognition region. In one embodiment, when a touch event occurs, the flexible circuit board  40  may merely provide an alternating current signal to the second electrode  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. Further, after removing the portion that is bonded to and overlaps the flexible circuit board  40 , the remaining portion of each second electrode  301  may form a square structure as much as possible, and the area of the remaining portion may be approximately 25 mm 2  as much as possible, which may facilitate to meet the area required for identifying one fingerprint. 
       FIG. 7  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure. For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 7  illustrates a transparency filling. In certain embodiments, referring to  FIG. 7 , the second electrode  301  may have a rectangular shape. Along the first direction X, a length of the second electrode  301  may be A; and along the second direction Y, a length of the second electrode  301  may be B, where B&gt;A. In view of this, along the second direction Y, a length of the fingerprint recognition region (i.e., the region that is capable of achieving fingerprint detection when the touch subject touches the fingerprint recognition module) of the fingerprint recognition module  000  may be K, where B&gt;K. Along the first direction X, the length A of the second electrode  301  may satisfy 2 mm A 5 mm. Along the second direction Y, the length B of the second electrode  301  may satisfy B&gt;5 mm. Optionally, the length B of the second electrode  301  along the second direction Y may be in a range of approximately 6 mm-8 mm. 
     The disclosed embodiments may explain that each of the second electrodes  301  of the second electrode layer  30  arranged in an array of one row and multiple columns may have a rectangular shape. Along the first direction X, the length A of the second electrode  301  may satisfy 2 mm A 5 mm. Along the second direction Y, the length B of the second electrode  301  may satisfy B&gt;5 mm. Optionally, the length B of the second electrode  301  along the second direction Y may be in a range of approximately 6 mm-8 mm. The area occupied by the flexible circuit board  40  in the second direction Y may be reduced, which may facilitate to increase the area of the fingerprint recognition region. 
     In one embodiment, when a touch event occurs, if the touch subject such as a finger is located on two second electrodes  301 , the flexible circuit board  40  may merely provide an alternating current signal to the two second electrodes  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. Further, after removing the portion that is bonded to and overlaps the flexible circuit board  40 , the remaining portion (region C 2  shown in  FIG. 7 ) of the two second electrodes  301  involved in the touch event may form a square structure as much as possible, and the sum of areas of the remaining portion of the two second electrodes  301  may be approximately 25 mm 2  as much as possible, which may facilitate to meet the area required for identifying one fingerprint. 
       FIG. 8  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure; and  FIG. 9  illustrates a schematic C-C′ sectional view of the fingerprint recognition module in  FIG. 8 . For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 8  illustrates a transparency filling. In certain embodiments, referring to  FIG. 8  and  FIG. 9 , in the fingerprint recognition module, a barrier spacer  50  may be disposed between adjacent two second electrodes  301 . 
     The disclosed embodiments may explain that the plurality of first electrodes  101  of the first electrode layer  10  may be arranged in an array of multiple rows and multiple columns, while the plurality of second electrodes  301  of the second electrode layer  30  may be arranged in an array of one row and multiple columns. In other words, along the second direction Y, there may be merely one row of second electrodes  301 ; and along the first direction X, the plurality of second electrodes  301  may be arranged in sequence. Optionally, one second electrode  301  in the disclosed embodiments may overlap at least two first electrodes  101 . In one embodiment, a quantity of the second electrodes  301  of the second electrode layer  30  may be more than one, and the plurality of second electrodes  301  may be arranged along the first direction X. In the second direction, each second electrode  301  may be directly bonded to the flexible circuit board  40  for electrical connection. 
     When the touch event occurs, the flexible circuit board  40  may merely provide the alternating current signal to the second electrode  301  involved in the touch event, and may not provide the signals to the remaining second electrodes  301 . Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. Moreover, when the plurality of second electrodes  301  are arranged along the first direction X, the barrier spacer  50  may be disposed between adjacent two second electrodes  301  to insulate the adjacent two second electrodes  301  from each other. Further, the barrier spacer  50  may fill and level up a gap between the adjacent two second electrodes  301 , which may facilitate the flatness of the entire fingerprint recognition module  000 . 
     Optionally, referring to  FIG. 8 , the barrier spacer  50  may be extended along the second direction Y, and an orthographic projection of the barrier spacer  50  on a plane of the flexible circuit board  40  may at least partially overlap the flexible circuit board  40 . 
     The disclosed embodiments may explain that the barrier spacer  50  configured to insulate the two second electrodes  301  may be extended along the second direction Y to a position where the second electrode overlaps the flexible circuit board  40 , which may fill and level up the gap between adjacent two pins  401  of the flexible circuit board  40 , and may facilitate to improve the bonding yield of the second electrodes  301  and the flexible circuit board  40 . 
     In certain embodiments, the second electrode layer  30  may be formed by a vacuum process such as a sputtering process. The second electrode layer  30  formed by the sputtering process may be substantially thin, in view of this, the barrier spacer  50  may not be disposed between adjacent two second electrodes  301 , which may facilitate to reduce the process steps and improve the process efficiency. 
       FIG. 10  illustrates a schematic D-D′ sectional view of the fingerprint recognition module in  FIG. 7 . In certain embodiments, referring to  FIG. 7  and  FIG. 10 , the fingerprint recognition module  000  may also include a driving circuit layer  60 . The driving circuit layer  60  may be electrically connected to the first electrode layer  10  (the electrical connection relationship may not be shown in  FIG. 10 ). It should be understood that an insulating layer may be disposed between the driving circuit layer  60  and the first electrode layer  10 , which may not be filled in  FIG. 10 . Optionally, the driving circuit layer  60  may be disposed between the substrate  00  and the first electrode layer  10 , to achieve electrical connection with the first electrode layer  10 . 
     The driving circuit layer  60  may include a plurality of driving circuits  601 , and the plurality of driving circuits  601  may be arranged in an array.  FIG. 10  illustrates the driving circuit using a block diagram. In specific implementation, the structure of the driving circuit  601  formed in the driving circuit layer  60  may include circuit connection structures such as a transistor, a capacitor, and a signal line, etc., as long as the driving circuit  601  is capable of achieving the fingerprint recognition function with ultrasonic technology, which may not be limited by the present disclosure. Optionally, the driving circuits  601  of the driving circuit layer  60  may be electrically connected to the first electrodes  101  in a one-to-one correspondence. 
     In a plane parallel to the first electrode layer  10 , the interval between adjacent two second electrodes  301  may be located between adjacent two columns of driving circuits  601 . 
     The disclosed embodiments may explain that the driving signal between the first electrode  101  and the second electrode  301  may be provided by each driving circuit  601  of the driving circuit layer  60 . Optionally, the driving circuit layer  60  may be disposed between the substrate  00  and the first electrode layer  10 , to achieve the electrical connection with the first electrode layer  10 . In the plane parallel to the first electrode layer  10 , the interval between the adjacent two second electrodes  301  may be disposed between adjacent two columns of driving circuits  601 . Therefore, the interval between the adjacent two second electrodes  301  may not involve the driving circuit  601 , which may facilitate to produce a desired driving induction relationship between the second electrode  301  and each corresponding driving circuit  601 . 
     When a touch event occurs, the flexible circuit board  40  may merely provide an alternating current signal and each driving signal to the second electrode  301  involved in the touch event through the driving circuit  601 , and may not provide signals to the remaining electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at a position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. According to the voltage signals that change differently, the positions of the valleys and ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs, and may be ultimately read and be converted to a fingerprint image by the flexible circuit board  40  through the driving circuit  601 , to achieve the fingerprint recognition. 
       FIG. 11  illustrates a schematic C-C′ sectional view of the fingerprint recognition module in  FIG. 8 . In certain embodiments, referring to  FIG. 8  and  FIG. 11 , the fingerprint recognition module  000  may further include a driving circuit layer  60 . The driving circuit layer  60  may be electrically connected to the first electrode layer  10  (the electrical connection relationship may not be shown in  FIG. 11 ). It should be understood that an insulating layer may be disposed between the driving circuit layer  60  and the first electrode layer  10 , which may not be filled in  FIG. 11 . Optionally, the driving circuit layer  60  may be disposed between the substrate  00  and the first electrode layer  10 , to achieve electrical connection with the first electrode layer  10 . An insulating barrier spacer  50  may be disposed between adjacent two second electrodes  301 . 
     The driving circuit layer  60  may include a plurality of driving circuits  601 , and the plurality of driving circuits  601  may be arranged in an array.  FIG. 11  illustrates the driving circuit using a block diagram. In specific implementation, the structure of the driving circuit  601  formed in the driving circuit layer  60  may include circuit connection structures such as a transistor, a capacitor, and a signal line, etc., as long as the driving circuit  601  is capable of achieving the fingerprint recognition function with ultrasonic technology, which may not be limited by the present disclosure. Optionally, the driving circuits  601  in the driving circuit layer  60  may be electrically connected to the first electrodes  101  in a one-to-one correspondence. 
     In the plane parallel to the first electrode layer  10 , the barrier spacer  50  between adjacent two second electrodes  301  may be located between adjacent two columns of driving circuits  601 . 
     The disclosed embodiments may explain that the driving signal between the first electrode  101  and the second electrode  301  may be provided by each driving circuit  601  of the driving circuit layer  60 . Optionally, the driving circuit layer  60  may be disposed between the substrate  00  and the first electrode layer  10 , to achieve the electrical connection with the first electrode layer  10 . In the plane parallel to the first electrode layer  10 , the barrier spacer  50  between the adjacent two second electrodes  301  may be located between adjacent two columns of driving circuits  601 . Therefore, the barrier spacer  50  may be prevented from overlapping the driving circuit  601  as much as possible, which may facilitate to produce a desired driving induction relationship between the second electrode  301  and each corresponding driving circuit  601 . 
     When a touch event occurs, the flexible circuit board  40  may merely provide an alternating current signal and each driving signal to the second electrode  301  involved in the touch event through the driving circuit  601 , and may not provide signals to the remaining electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at a position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. According to the voltage signals that change differently, the positions of the valleys and ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs, and may be ultimately read and be converted to a fingerprint image by the flexible circuit board  40  through the driving circuit  60 , to achieve the fingerprint recognition. 
     It should be noted that  FIG. 10  and  FIG. 11  merely schematically illustrate the structure of the driving circuit layer  60 . In specific implementation, the driving circuit layer  60  may also include multiple metal conductive film layers for forming transistors, capacitors, etc., of each driving circuit  601 , and the structure of the multiple metal conductive film layers of the driving circuit layer  60  may not be limited by the present disclosure, and may be determined according to the actual circuit connection structure of the driving circuit  601 . 
       FIG. 12  illustrates a schematic top-view of another fingerprint recognition module consistent with disclosed embodiments of the present disclosure; and  FIG. 13  illustrates a schematic E-E′ sectional view of the fingerprint recognition module in  FIG. 12 . For illustrative purposes, to clearly illustrate the positional relationship between the first electrode layer and the second electrode layer,  FIG. 12  illustrates a transparency filling. In certain embodiments, referring to  FIG. 12  and  FIG. 13 , in the fingerprint recognition module  000 , the driving circuit layer  60  may at least include a common signal line DB, and the common signal line DB may be extended along the second direction Y. The common signal line DB may include at least a first common signal line DB 1 . 
     An orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  may at least partially overlap an orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . 
     The disclosed embodiments may explain that the driving circuit layer  60  may include a plurality of common signal lines DB. Optionally, the common signal line DB may be electrically connected to each driving circuit  601  (not shown in the Figure), and the common signal line DB may be configured to provide a common voltage signal to each driving circuit  601 . In one embodiment, the common signal line DB may be extended along the second direction Y. The orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  may at least partially overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . In other words, the first common signal line DB 1  of the driving circuit layer  60  may be disposed at a position of the barrier spacer  50 , and the barrier spacer  50  may overlap the first common signal line DB 1 . Because the barrier spacer  50  is configured to insulate the adjacent two second electrodes  301 , the barrier spacer  50  may often have a substantially wide width in the first direction X. Therefore, the first common signal line DB 1  may be disposed at the position of the barrier spacer  50 , which may facilitate to further reduce the power loss by increasing the line width of the first common signal line DB 1 . Further, when the driving circuit  601  reads fingerprint information and performs data conversion to form a fingerprint image, charging may be uniform, which may facilitate to improve the dynamic sampling range of the driving circuit  601 . 
     Optionally, the orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  may merely partially overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . Alternatively, the orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  may be fully within a range of the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . In other words, the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10  may fully cover the orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  (as shown in  FIG. 13 ), which may facilitate to further increase the line width of the first common signal line DB 1 , and may further reduce the power loss of the driving circuit  601 . 
     In certain embodiments, referring to  FIG. 12  and  FIG. 13 , the common signal line DB configured to provide the common voltage signal to each driving circuit  601  may further include a second common signal line DB 2 . An orthographic projection of the second common signal line DB 2  on the plane of the first electrode layer  10  may not overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . A line width W 4  of the second common signal line DB 2  may be less than the line width W 3  of the first common signal line DB 1 . 
     The disclosed embodiments may explain that the driving circuits  601  in the driving circuit layer  60  may be electrically connected to the first electrodes  101  in a one-to-one correspondence. In addition to the first common signal line DB 1  overlapped with the barrier spacer  50 , the driving circuit layer  60  may further include a second common signal line DB 2  extended along the second direction Y and disposed at an interval position between adjacent two columns of the first electrodes  101 . The second common signal line DB 2  may be configured to provide a common voltage signal to each driving circuit  601 . Because the orthographic projection of the second common signal line DB 2  on the plane of the first electrode layer  10  does not overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 , the line width W 4  of the second common signal line DB 2  may be less than the line width W 3  of the first common signal line DB 1 , which may facilitate to save the layout space of the driving circuit layer  60 , and may avoid reducing the space of the driving circuit layer  60  caused by disposing too many common signal lines DB with a substantially large line width, thereby facilitating the layout of the various components in the driving circuit  601  of the driving circuit layer  60 . 
     In certain embodiments, referring to  FIG. 12  and  FIG. 13 , the common signal line DB configured to provide the common voltage signal to each driving circuit  601  may include the first common signal line DB 1  and the second common signal line DB 2 . Both the first common signal line DB 1  and the second common signal line DB 2  may be extended along the second direction Y. The orthographic projection of the first common signal line DB 1  on the plane of the first electrode layer  10  may at least partially overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . The orthographic projection of the second common signal line DB 2  on the plane of the first electrode layer  10  may not overlap the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10 . The line width W 4  of the second common signal line DB 2  may be less than the line width W 3  of the first common signal line DB 1 . 
     The driving circuit layer  60  may further include a plurality of sub-connection lines DB 3 , and the plurality of sub-connection lines DB 3  may be connected to each other through the common signal line DB. The sub-connection line DB 3  may be extended along the first direction X. 
     The disclosed embodiments may explain that the first common signal line DB 1  and the second common signal line DB 2  may be connected to each other through the sub-connection lines DB 3  extended along the first direction X. In other words, the first common signal line DB 1 , the second common signal line DB 2  and the sub-connection line DB 3  may be interlaced to form a grid structure, such that merely one pin (not shown in the Figure) for providing a common voltage signal may be disposed on the flexible circuit board  40 . The common voltage signal may be provided to all the driving circuits  601  of the driving circuit layer  60  through the pin for providing the common voltage signal and the sub-connection lines DB 3  for connecting the first common signal line DB 1  with the second common signal line DB 2 , which may facilitate to reduce the quantity of pins of the flexible circuit board  40 , thereby reducing the occupied area of the flexible circuit board  40 . 
     Optionally, the line width of the common signal line DB may be greater than a line width W 5  of the sub-connection line DB 3 . The disclosed embodiments may further explain that because the sub-connection line DB 3  extended along the first direction X may not be located in a region covered by the barrier spacer  50 , the line width W 5  of the sub-connection line DB 3  may be substantially narrow. In one embodiment, the line width W 5  of the sub-connection line DB 3  may not only be smaller than the line width W 3  of the first common signal line DB 1 , but also be smaller than the line width W 4  of the second common signal line DB 2 . In another embodiment, the line width W 5  of the sub-connection line DB 3  may be equal to the line width W 4  of the second common signal line DB 2 , while may be smaller than the line width W 3  of the first common signal line DB 1  (as shown in  FIG. 12 ), which may prevent the sub-connection line DB 3  from occupying too much space of the driving circuit layer  60 . 
       FIG. 14  illustrates a schematic diagram of an equivalent circuit connection of the plurality of driving circuits of a driving circuit layer consistent with disclosed embodiments of the present disclosure;  FIG. 15  illustrates a schematic diagram of a connection structure of a driving circuit in  FIG. 14 ; and  FIG. 16  illustrates an operating timing diagram of the driving circuit. In certain embodiments, referring to  FIGS. 12-16 , the driving circuit layer  60  may include the plurality of driving circuits  601 , and may further include a scanning line Scan, a detection signal line Data, a power signal line Vcc, a sampling signal line SP, and the common signal line DB. 
     The driving circuit  601  may include a first transistor M 1 , a second transistor M 2 , a third transistor M 3 , and a storage capacitor Cp. The first electrode  101  of the first electrode layer  10  may be connected to a storage node Xn. A gate of the first transistor M 1  may be connected to the storage node Xn, a first terminal of the first transistor M 1  may be connected to the power signal line Vcc, and the second terminal of the first transistor M 1  may be connected to a first terminal of the third transistor M 3 . A gate of the second transistor M 2  may be connected to the sampling signal line SP, a first terminal of the second transistor M 2  may be connected to the storage node Xn, and a second terminal of the second transistor M 2  may be connected to the common signal line DB. A gate of the third transistor M 3  may be connected to the scanning line Scan, and a second terminal of the third transistor M 3  may be connected to the detection signal line Data. A first terminal of the storage capacitor Cp may be connected to the storage node Xn, and a second terminal of the storage capacitor Cp may be connected to the power signal line Vcc. 
     The driving circuit layer  60  may include a plurality of driving circuits  601  arranged in an array. Optionally, each driving circuit  601  may be electrically connected to one first electrode  101  of the first electrode layer  10  through the storage node Xn, to achieve the fingerprint recognition function. The driving circuit layer  60  may further include a plurality of scanning lines Scan, a plurality of detection signal lines Data, a plurality of power signal lines Vcc, a plurality of sampling signal lines SP, and a plurality of common signal lines DB. The scanning line Scan, the detection signal line Data, the power signal line Vcc, the sampling signal line SP and the common signal line DB may be electrically connected to the flexible circuit board  40 , to achieve input and output of the signal. 
     The scanning line Scan may be configured to provide a scanning signal to the driving circuit  601 , to control the turn-on and turn-off of the third transistor M 3 . The detection signal line Data may be configured, when the third transistor M 3  is turned on, to receive the information reflecting the charges stored in the storage capacitor Cp, i.e., to receive the signal after performing the fingerprint detection. The power signal line Vcc may be configured to provide the operating power of the driving circuit  601 . The sampling signal line SP may be configured to control the turn-on and turn-off of the second transistor M 2 . The common signal line DB may be configured to provide the common voltage signal to the driving circuit  601  when the second transistor M 2  is turned on. Referring to  FIG. 16 , the operating stage of the driving circuit  601  may include an excitation stage T 1 , a sampling stage T 2 , and a reading stage T 3 . 
     First, in the excitation stage T 1 , when a touch event occurs, the flexible circuit board  40  may merely provide alternating current signal (transmit signal) to the second electrode  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at a position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. 
     In the following sampling stage T 2 , after the excitation stage T 1  ends, the remaining shock of the ultrasonic oscillation may affect the piezoelectric layer  20  and generate electrical signals. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. The electrical signals with different changes generated by the piezoelectric layer  20  may be converted into different charges stored in the storage capacitor Cp through sampling. 
     In the ultimate reading stage T 3 , according to the voltage signals that change differently, the positions of the valleys and ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs. The detection signal line Data may receive the information reflecting the charges stored in the storage capacitor Cp, and the flexible circuit board  40  may read the information and may perform a data conversion to form a fingerprint image, to complete the fingerprint recognition. 
     The disclosed embodiments may explain that the first electrode  101  of the first electrode layer  10  may be connected to the storage node Xn, such that the fingerprint electrical signal received by the first electrode  101  may be stored in the storage capacitor Cp. A signal reading unit formed by the first transistor M 1  and the third transistor M 3  may be configured to read the fingerprint electrical signal stored in the storage capacitor Cp, i.e., the voltage signal received by the first electrode  101 . The first terminal of the first transistor M 1  may be connected to a fixed voltage inputted from the power signal line Vcc, and the gate of the third transistor M 3  may be connected to the scanning line Scan. The scanning line Scan may input an instruction of whether to read the detection signal, to turn on the third transistor M 3  and to output the fingerprint electrical signal stored in the storage capacitor Cp through the detection signal line Data. In the process of storing the fingerprint electrical signal received by the first electrode  101  in the storage capacitor Cp, the second transistor M 2  may be turned on through the sampling signal line SP, and the common voltage signal may be applied to the second terminal of the second transistor M 2  through the common signal line DB, such that the alternating current signal received by the first electrode  101  may be raised, and a fingerprint detection signal with a substantially large contrast may be obtained. 
     It should be understood that the disclosed embodiments may provide a connection structure of the driving circuit  601  that is capable of achieving the fingerprint recognition based on ultrasonic technology, which may not be limited to such circuit structure. In specific implementation, the circuit structure may be any other detection circuit that is capable of achieving ultrasonic fingerprint recognition, and  FIG. 16  merely illustrates the operating timing diagram of the driving circuit  601  as an example. The driving circuit  601  may also be driven by any other timing according to actual conditions, which may not be repeated herein. 
     In certain embodiments, referring to  FIGS. 12-16 , the scanning line Scan may be extended along the second direction Y. 
     The disclosed embodiments may explain that in the driving circuit layer  60 , the scanning line Scan connected to each driving circuit  601  may have an extension direction same as the second electrode  301 , and both may be extended along the second direction Y. When a touch event occurs, the flexible circuit board  40  may merely provide an alternating current signal to the second electrode  301  involved in the touch event through the driving circuit  601 , and the flexible circuit board  40  may merely provide the driving signal to the scanning line Scan corresponding to the second electrode  301  involved in the touch event. Therefore, the flexible circuit board  40  may merely drive multiple columns of driving circuits  601  corresponding to the second electrode  301  involved in the touch event to achieve the fingerprint recognition, which may facilitate to reduce power consumption. 
     In certain embodiments, referring to  FIG. 8  and  FIG. 11 , the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10  may not overlap the first electrode  101 . 
     The disclosed embodiments may explain that in the plane parallel to the first electrode layer  10 , the barrier spacer  50  between adjacent two second electrodes  301  may be disposed between adjacent two rows of first electrodes  101 . In other words, the orthographic projection of the barrier spacer  50  on the plane of the first electrode layer  10  may not overlap the first electrode  101 , such that the first electrode  101  may be prevented from overlapping the barrier spacer  50  as much as possible, which may facilitate to increase the facing area of the second electrode  301  and corresponding first electrode  101 , may prevent the stagger of the first electrode  101  and the second electrode  301  from affecting the driving voltage applied between the first electrode  101  and the second electrode  301 , and may facilitate to improve the accuracy of fingerprint recognition. 
     In certain embodiments, referring to  FIG. 8  and  FIG. 11 , in one embodiment, along the first direction X, a width W 6  of the barrier spacer  50  may be in a range of approximately 1 um-50 um. 
     The disclosed embodiments may explain that the barrier spacer  50  between the adjacent two second electrodes  301  may be substantially wide, and the width W 6  of the barrier spacer  50  may be in a range of approximately 1 um-50 um. If the width W 6  of the barrier spacer  50  is too small, the line width of the common signal line DB that overlaps the barrier spacer  50  may not effectively increase, and the power consumption may not be effectively reduced. If the width W 6  of the barrier spacer  50  is too large, the layout area of the second electrode  301  may be affected. Therefore, in the present disclosure, the width of the barrier spacer  50  may be in a range of approximately 1 um-50 um, which may not only facilitate to increase the line width of the common signal line DB that overlaps the barrier spacer  50  to effectively reduce the power consumption, but also ensure the second electrode layer  30  to have sufficient space for disposing the second electrode  301  as much as possible. 
     In certain embodiments, referring to  FIG. 8  and  FIG. 11 , the barrier spacer  50  may be made of a material including an organic material. 
     The disclosed embodiments may explain that the barrier spacer  50  may be made of a material including an organic material, such as acrylic, polyimide or any other resin material. The organic material may have desired buffering performance. While making the barrier spacer  50  have an insulating effect, the barrier spacer  50  may buffer the pressure between adjacent two second electrodes  301 . In addition, in the manufacturing process, the organic material may facilitate the fabrication by coating. Therefore, in the present disclosure, the barrier spacer  50  may be made of the organic material, and a substantially thick film layer may be conveniently formed as the barrier spacer  50  in the present disclosure. 
     Optionally, when forming the second electrode  301  in the present disclosure, because the second electrode  301  requires high precision, and processes such as photolithography may not form a pattern with substantially high precision. In the present disclosure, when forming the second electrode  301 , the barrier spacer  50  may be used to form the pattern. In other words, an organic material layer may be first coated on the piezoelectric layer  20 , and a plurality of barrier spacers  50  may be formed by a photolithography process. Then, the second electrode layer  30  may be formed by a coating process. Due to the action of the barrier spacer  50 , the second electrodes  301  extended along the second direction Y with high precision may be formed between adjacent barrier spacers  50 . Ultimately, the second electrodes may be directly bonded and connected to the flexible circuit board  40 . 
     In certain embodiments, referring to  FIG. 8  and  FIG. 11 , a difference between an acoustic resistance of the material for forming the barrier spacer  50  and an acoustic resistance of the material for forming the first electrode  101  and the second electrode  301  may be less than or equal to 9 million Rayleigh (MRayl). Acoustic resistance may be acoustic impedance, which may be a characteristic of the material, and may refer to a complex ratio of the sound pressure of the medium on a certain area of the wave surface over a volume velocity passing through such area, i.e., the resistance that the medium displacement needs to overcome when the sound wave is transmitted. The greater the acoustic impedance, the greater the sound pressure required to push the medium, and the smaller the acoustic impedance, the smaller the sound pressure required to push the medium. The measured value of the acoustic impedance may often have a unit of million Rayleigh (MRayl). 
     The disclosed embodiments may explain that the acoustic resistance of the material for forming the barrier spacer  50  may be adjacent to the acoustic resistance of the material for forming the first electrode  101  and the second electrode  301 . In other words, the difference between the acoustic resistance of the material for forming the barrier spacer  50  and the acoustic resistance of the material for forming the first electrode  101  and the second electrode  301  may be less than or equal to 9 MRayl. Therefore, when performing the ultrasonic fingerprint recognition, the phenomenon of ultrasonic waveform distortion near the barrier spacer  50  may be prevented. 
     In certain embodiments, referring to  FIG. 8  and  FIG. 11 , a surface of the barrier spacer  50  adjacent to the first electrode layer  10  may be a first surface  50 A, and a surface of the second electrode  301  adjacent to the first electrode layer  10  may be a second surface  301 A. The first surface  50 A and the second surface  301 A may be disposed in a same plane. 
     The disclosed embodiments may explain that the first surface  50 A of the barrier spacer  50  adjacent to the first electrode layer  10  and the second surface  301 A of the second electrode  301  adjacent to the first electrode layer  10  may be disposed in the same plane. Therefore, the barrier spacer  50  may not be extended to the piezoelectric layer  20  as much as possible, which may prevent the barrier spacer  50  from damaging the uniformity of the piezoelectric layer  20 , and may facilitate to improve the uniformity of the ultrasonic waves generated by the piezoelectric layer  20  when vibrating. 
     The present disclosure also provides a display panel.  FIG. 17  illustrates a schematic diagram of a display panel consistent with disclosed embodiments of the present disclosure. In certain embodiments, referring to  FIGS. 1-17 , a display panel  111  may include the fingerprint recognition module  000  provided in the above-disclosed embodiments. For illustrative purposes,  FIG. 17  illustrates a mobile phone as an example to describe the display panel  111 . The display panel  111  may be a computer, a TV, a vehicle-mounted display panel, or any other display panel with a display function, which may not be limited by the present disclosure. The display panel  111  in the present disclosure may have the beneficial effects of the fingerprint recognition module  000  in the present disclosure, which may refer to specific descriptions of the fingerprint recognition module  000  in the foregoing embodiments, and may not be repeated herein. 
     It should be understood that for illustrative purposes, the display panel  111  may have an area different from the fingerprint recognition module  000  as an example. The fingerprint recognition module  000  may be disposed merely in the region where fingerprint recognition is required (as shown in  FIG. 17 ), which may not be limited by the present disclosure. The area of the display panel  111  may be adjacent to or same as the area of the fingerprint recognition module  000 , to achieve the full-screen fingerprint recognition. 
       FIG. 18  illustrates a schematic F-F′ cross-sectional view of the display panel in  FIG. 17 . In certain embodiments, referring to  FIGS. 1-18 , the display panel  111  may further include a display module  222  that is disposed opposite to the fingerprint recognition module  000 . In one embodiment, the display module  222  may be a liquid-crystal display module including an array substrate, a liquid-crystal layer, and a color film substrate, etc. In another embodiment, the display module  222  may be an organic light-emitting display module including an organic light-emitting layer, and an encapsulation layer, etc., which may not be limited by the present disclosure. In the display panel  111 , the fingerprint recognition module  000  may be disposed on a side of the display module  222  facing away from a light-exiting surface G of the display panel  111 , and the first electrode layer  10  may be disposed on a side of the second electrode layer  30  adjacent to the display module  222 . 
     The disclosed embodiments may explain that the display panel  111  may include the fingerprint recognition module  000 . The fingerprint recognition module  000  may be disposed on the side of the display module  222  facing away from the light-exiting surface G of display panel  000 , and the first electrode layer  10  may be disposed on the side of the second electrode layer  30  adjacent to the display module  222 . Optionally, an insulating protection layer  80  (not filled in the Figure) may be disposed on a side of the second electrode layer  30  facing away from the first electrode layer  10 , to protect the fingerprint recognition module  000 . 
     The fingerprint recognition module  000  may be disposed on the side of the display module  222  facing away from the light-exiting surface G of display panel  000 , and the first electrode layer  10  may be disposed on the side of the second electrode layer  30  adjacent to the display module  222 . Because the ultrasonic waves may be reflected at an interface between medium and air, through configuring the fingerprint recognition module  000  to be disposed on the side of the display module  222  facing away from the light-exiting surface G of the display panel  000 , and the first electrode layer  10  to be disposed on the side of the second electrode layer  30  adjacent to the display module  222 , i.e., the fingerprint recognition module  000  may be attached upside down to the display module  222 , which may effectively use the reflected ultrasonic signal, thereby facilitating to improve the accuracy of fingerprint recognition. 
     It should be understood that the display panel  111  may be a liquid-crystal display panel, or an organic light-emitting display panel.  FIG. 17  and  FIG. 18  merely illustrate exemplary drawings of the structure of the display panel  111 . In specific implementation, the structure of the display panel  111  may be understood with reference to the structure of the display panel in the related art. 
       FIG. 19  illustrates a schematic F-F′ cross-sectional view of another display panel in  FIG. 17 . In certain embodiments, referring to  FIGS. 1-17  and  FIG. 19 , the display panel  111  may further include a touch-control layer  70 . The touch-control layer  70  may be located at a side of the display panel  111  adjacent to the light-exiting surface G. Optionally, when the display module  222  is a liquid-crystal display module including an array substrate, a liquid-crystal layer, and a color film substrate, etc., the touch-control layer  70  may be formed on a side of the color film substrate of the display module  222  facing away from the liquid-crystal layer. Optionally, when the display module  222  is an organic light-emitting display module including an organic light-emitting layer, and an encapsulation layer, etc., the touch-control layer  70  may be formed on a side of the encapsulation layer facing away from the organic light-emitting layer. A protection structure such as a cover  90  may encapsulate the touch-control layer  70  into the display panel  111  (not shown in the Figure). 
     The disclosed embodiments may explain that the display panel  111  may further include the touch-control layer  70 , and the touch-control layer  70  may be located at the side of the display panel  111  adjacent to the light-exiting surface G, such that the display panel  111  may achieve the touch-control function. Through the touch-control layer  70 , the location where the touch event occurs may be determined, to achieve the detection of the touch location. Then, through the fingerprint recognition module  000 , the fingerprint recognition may be performed merely on location where the touch event occurs. Therefore, any additional touch-control device such as a capacitive touch-control panel may not need to be formed, while reducing the cost of the display panel, the fingerprint recognition may be achieved through the disclosed fingerprint recognition module  000 , thereby reducing the power consumption. 
     The present disclosure also provides a driving method of a display panel.  FIG. 20  illustrates a schematic flowchart of a driving method of a display panel consistent with disclosed embodiments of the present disclosure. In certain embodiments, referring to  FIGS. 1-17  and  FIGS. 19-20 , the driving method may be configured to drive the display panel in the present disclosure to perform the touch detection and fingerprint recognition. The driving method may include following. 
     In S 10 : determining a touch position of a finger through the touch-control layer  70 , for the touch detection. 
     In S 20 : determining the second electrode  301  corresponding to the touch position of the finger. 
     In S 30 : providing an excitation signal only to the second electrode  301  corresponding to the touch position of the finger, where the first electrode  101  may be connected to the common potential, and the piezoelectric layer  20  between the second electrode  301  and the first electrode  101  corresponding to the touch position of the finger may generate ultrasonic waves. 
     In S 40 : performing, by the driving circuit  601  corresponding to the second electrode  301  corresponding to the touch position of the finger, ultrasonic fingerprint recognition, for the fingerprint recognition. 
     Specifically, in the disclosed driving method of the display panel, the fingerprint recognition may be performed after completing the touch detection, and each second electrode  301  may be driven separately. In other words, when a touch event occurs, the flexible circuit board  40  may merely provide alternating current signal to the second electrode  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at a position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. According to the voltage signals that change differently, the positions of the valleys and ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs, and may be ultimately read and be converted to a fingerprint image by the flexible circuit board  40 , to achieve the fingerprint recognition. Further, when the touch event occurs, the flexible circuit board  40  may merely provide the alternating current signal to the second electrode  301  involved in the touch event, and may not provide the signals to the remaining second electrodes  301 . Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. 
       FIG. 21  illustrates a schematic flowchart of another driving method of a display panel consistent with disclosed embodiments of the present disclosure. In certain embodiments, referring to  FIGS. 1-17 ,  FIG. 19 , and  FIG. 21 , the driving method may be configured to drive the display panel in the present disclosure to perform the touch detection and fingerprint recognition. The driving method may include following. 
     In S 10 : determining a touch position of a finger through the touch-control layer  70 , for the touch detection. 
     In S 20 : determining the second electrode  301  corresponding to the touch position of the finger. 
     In S 301 : in an excitation stage, providing an alternating current signal only to the second electrode  301  corresponding to the touch position of the finger, where the piezoelectric layer  20  generates ultrasonic waves. 
     In S 302 : in a sampling stage, generating, by the piezoelectric layer  20 , different electrical signals when ultrasonic waves are reflected by the fingerprint valleys and fingerprint ridges of the finger back to the piezoelectric layer  20 , and converting the different electrical signals into different charges stored in the storage capacitor Cp in the driving circuit  601  through sampling. 
     In S 303 : in a reading stage, proving a scanning signal through the scanning line Scan, and reading the charges stored in the storage capacitor Cp of each driving circuit  601  through the detection signal line Data. 
     In S 304 : forming, by the flexible circuit board  40 , a fingerprint image by reading information reflecting the charges stored in the storage capacitor Cp and performing a data conversion, to complete the fingerprint recognition. 
     The disclosed embodiments may explain that in the disclosed driving method of the display panel, the fingerprint recognition may be performed after completing the touch detection. After determining the position where the touch event occurs, first, in the excitation stage T 1 , the flexible circuit board  40  may merely provide alternating current signal (transmit signal) to the second electrode  301  involved in the touch event, and may not provide signals to the remaining second electrodes  301 . Therefore, merely the driving voltage applied between the first electrode  101  and the second electrode  301  located at the position where the touch event occurs may change constantly, such that the piezoelectric layer  20  may vibrate and generate ultrasonic waves. In the following sampling stage T 2 , after the excitation stage T 1  ends, the remaining shock of the ultrasonic oscillation may affect the piezoelectric layer  20  and generate electrical signals. Because the fingerprint includes valleys and ridges, vibration intensities of ultrasonic waves reflected by the fingerprint back to the piezoelectric layer  20  may be different, and the electrical signals generated by the ultrasonic waves reflected by valleys and ridges of the fingerprint back to the piezoelectric layer  20  may change differently. The electrical signals with different changes generated by the piezoelectric layer  20  may be converted into different charges stored in the storage capacitor Cp through sampling. In the ultimate reading stage T 3 , according to the voltage signals that change differently, the positions of the valleys and ridges of the fingerprint may be determined, the determination result may be fed back to the first electrodes  101  located at the position where the touch event occurs. The detection signal line Data may receive the information reflecting the charges stored in the storage capacitor Cp, and the flexible circuit board  40  may read the information and may perform the data conversion to form a fingerprint image, to complete the fingerprint recognition. 
     The present disclosure also provides a display device.  FIG. 22  illustrates a schematic top view of a display device consistent with disclosed embodiments of the present disclosure. In one embodiment, referring to  FIG. 22 , the display device  1111  may include the display panel  111  provided in the above-disclosed embodiments. For illustrative purposes,  FIG. 22  illustrates a mobile phone as an example to describe the display device  1111 . The display device  1111  may be a computer, a TV, a vehicle-mounted display device, or any other display device with a display function, which may not be limited by the present disclosure. The display device  1111  in the present disclosure may have the beneficial effects of the display panel  111  in the present disclosure, which may refer to specific descriptions of the display panel  111  in the foregoing embodiments, and may not be repeated herein. 
     The fingerprint recognition module, the display panel and display device in the present disclosure may at least include following beneficial effects. In the present disclosure, the second electrode layer in the fingerprint recognition module may include a plurality of second electrodes, and each second electrode may be used as a driving electrode. The flexible circuit board configured to provide the driving voltage signal to the fingerprint recognition module and to read the fingerprint detection signal may be directly bonded and connected to the second electrodes. In the prior art, the second electrode is often connected to the flexible circuit board through a thin lead to achieve the transmission of an electrical signal. A width of the lead used as a wiring is significantly different from a width of the second electrode used as a driving electrode, and the width of the general lead is much smaller and is a few hundredths or even a few thousandths of the width of the second electrode. The size of the line width may affect the size of the cross-sectional area of a resistor, thereby affecting the resistance value of the resistor. The smaller the line width, the smaller the cross-sectional area, and the greater the resistance. Therefore, when the conditions are basically the same, the resistance of the lead used as the wiring may be much greater than the resistance of the second electrode used as the driving electrode. 
     Therefore, in the disclosed embodiments, the flexible circuit board configured to provide the driving voltage signal to the fingerprint recognition module and to read the fingerprint detection signal may be directly bonded and connected to the second electrodes, and the lead may not be used in the module structure, which may effectively avoid the loss of the driving signal transmitted between the flexible circuit board and the second electrode and serious power loss due to large impedance of lead, thereby reducing the power loss of the fingerprint recognition module, achieving ultrasonic fingerprint recognition, and improving recognition performance. At the same time, when the touch event occurs, the flexible circuit board may merely provide the alternating current signal to the second electrode involved in the touch event, and may not provide the signals to the remaining second electrodes. Therefore, the power supply area may be reduced, and the capacitive load during driving process may be reduced, which may facilitate to further reduce the power consumption. 
     The description of the disclosed embodiments is provided to illustrate the present disclosure to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments illustrated herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.