CN111695388A

CN111695388A - Fingerprint identification structure, driving method thereof and display device

Info

Publication number: CN111695388A
Application number: CN201910199587.6A
Authority: CN
Inventors: 刘英明; 王海生; 丁小梁; 王鹏鹏; 李秀锋; 张晨阳; 李佩笑
Original assignee: BOE Technology Group Co Ltd
Current assignee: BOE Technology Group Co Ltd
Priority date: 2019-03-15
Filing date: 2019-03-15
Publication date: 2020-09-22
Anticipated expiration: 2039-03-15
Also published as: CN111695388B; WO2020186983A1

Abstract

A fingerprint identification structure, a driving method of the fingerprint identification structure, and a display device. The fingerprint identification structure comprises a first electrode layer, a piezoelectric material layer and a second electrode layer; the first electrode layer comprises a plurality of strip-shaped receiving electrodes arranged at intervals; the piezoelectric material layer is arranged on one side of the first electrode layer; the second electrode layer is arranged on one side, far away from the first electrode layer, of the piezoelectric material layer and comprises a plurality of strip-shaped driving electrodes arranged at intervals, each strip-shaped driving electrode extends along a first direction, each strip-shaped receiving electrode extends along a second direction, the first direction and the second direction are intersected, the strip-shaped driving electrodes and the strip-shaped receiving electrodes are intersected with each other to form a plurality of intersection regions, and the piezoelectric material layer is at least overlapped with the intersection regions. From this, the quantity of rete is in order to improve the light transmissivity in this fingerprint identification structure reducible this fingerprint identification structure to make this fingerprint identification structure can set up the luminous side at display panel, and then can reduce the consumption.

Description

Fingerprint identification structure, driving method thereof and display device

Technical Field

Embodiments of the present disclosure relate to a fingerprint identification structure, a driving method of the fingerprint identification structure, and a display device.

Background

The fingerprint identification technology is a technology which performs identification by comparing minutiae characteristic points of different fingerprints, thereby achieving an identity identification function. With the continuous development of smart phones, the technology of fingerprint identification under the screen has become one of the research hotspots and development directions in the current smart phone market. At present, the technology of fingerprint identification under a screen can be divided into a capacitive fingerprint identification technology under a screen, an ultrasonic fingerprint identification technology under a screen and an optical fingerprint identification technology under a screen. The under-screen ultrasonic fingerprint identification technology becomes the most ideal solution at present due to the advantages of strong penetrability, high identification degree, strong anti-pollution capability and the like.

The ultrasonic fingerprint identification technology under the screen realizes fingerprint identification through an ultrasonic fingerprint identification structure. Generally, the ultrasonic fingerprint identification structure is a three-layer structure including a driving electrode, a receiving electrode, and a piezoelectric layer therebetween. When a driving voltage is applied to the driving electrode and the receiving electrode, the piezoelectric layer is excited by the voltage to generate an inverse piezoelectric effect, and a first ultrasonic wave is emitted outwards. The first ultrasonic wave is reflected back to the second ultrasonic wave by the finger after contacting the finger. Because the fingerprint includes valley and ridge, so be reflected back to the second ultrasonic wave vibration intensity difference of piezoelectric layer by the fingerprint, at this moment, load fixed voltage to the drive electrode, then the piezoelectric layer can convert second ultrasonic wave into voltage signal, and this voltage signal passes through receiving electrode and transmits fingerprint identification module, judges the position of valley and ridge in the fingerprint according to this voltage signal.

Disclosure of Invention

The embodiment of the disclosure provides a fingerprint identification structure, a driving method of the fingerprint identification structure and a display device. The fingerprint identification structure comprises a first electrode layer, a piezoelectric material layer and a second electrode layer; the first electrode layer comprises a plurality of strip-shaped receiving electrodes arranged at intervals; the piezoelectric material layer is arranged on one side of the first electrode layer; the second electrode layer sets up and keeps away from one side of first electrode layer at the piezoelectric material layer and includes along the interval and set up a plurality of strip driving electrode, and each strip driving electrode extends along the first direction, and each strip receiving electrode extends along the second direction, and first direction and second direction are crossing, and a plurality of strip driving electrode and a plurality of strip receiving electrode intercross are in order to form a plurality of cross regions, piezoelectric material layer at least and a plurality of cross regional overlap, one strip receiving electrode with a plurality of strip driving electrode form a plurality ofly cross regions. From this, the quantity of rete is in order to improve the light transmissivity in this fingerprint identification structure reducible this fingerprint identification structure to make this fingerprint identification structure can set up the luminous side at display panel, and then can reduce the consumption.

At least one embodiment of the present disclosure provides a fingerprint recognition structure, including: the first electrode layer comprises a plurality of strip-shaped receiving electrodes which are arranged at intervals; a piezoelectric material layer disposed on one side of the first electrode layer; the second electrode layer is arranged on one side, far away from the first electrode layer, of the piezoelectric material layer and comprises a plurality of strip-shaped driving electrodes arranged at intervals, each strip-shaped driving electrode extends along a first direction, each strip-shaped receiving electrode extends along a second direction, the first direction is intersected with the second direction, the strip-shaped driving electrodes and the strip-shaped receiving electrodes are intersected with each other to form a plurality of intersection regions, the piezoelectric material layer is at least overlapped with the intersection regions, and one strip-shaped receiving electrode and the strip-shaped driving electrodes form a plurality of intersection regions.

For example, in a fingerprint identification structure provided by an embodiment of the present disclosure, the piezoelectric material layer includes sub piezoelectric material layers arranged at intervals, and each of the sub piezoelectric material layers extends along the first direction or the second direction.

For example, in a fingerprint identification structure provided by an embodiment of the present disclosure, the piezoelectric material layer includes a plurality of sub-piezoelectric material blocks, and the plurality of sub-piezoelectric material blocks are arranged in one-to-one correspondence with the plurality of intersection regions.

For example, in a fingerprint identification structure provided in an embodiment of the present disclosure, the second electrode layer further includes: and the retaining wall is positioned between two adjacent strip-shaped driving electrodes.

For example, in the fingerprint identification structure provided by an embodiment of the present disclosure, the size range of the retaining wall in the direction perpendicular to the piezoelectric material layer is 1 to 20 micrometers, and the size range of the second electrode layer in the direction perpendicular to the piezoelectric material layer is 1 to 20 micrometers.

For example, in the fingerprint identification structure provided by an embodiment of the present disclosure, the material of the second electrode layer includes one or more of copper, silver, and aluminum.

For example, an embodiment of the present disclosure provides a fingerprint identification structure further including: the fingerprint identification structure comprises an effective identification area and an edge area located at the periphery of the effective identification area, a plurality of cross areas are located in the effective identification area, and a plurality of receiving circuits are located in the edge area.

For example, in a fingerprint identification structure provided in an embodiment of the present disclosure, each of the receiving circuits includes: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and the strip-shaped receiving electrode, the first source electrode and the first electrode are connected to a storage node, the signal reading unit is configured to read an electric signal stored in the storage capacitor, and the first thin film transistor is an oxide thin film transistor.

For example, in a fingerprint identification structure provided in an embodiment of the present disclosure, the signal reading unit includes: a second thin film transistor including a second gate electrode, a second source electrode, and a second drain electrode; and a third thin film transistor including a third gate, a third source, and a third drain, the second gate being connected to the storage node, the second drain being connected to the third source, the second source being configured to apply a fixed voltage, the third gate being configured to apply a readout instruction signal, the third drain being configured to output a signal.

At least one embodiment of the present disclosure also provides a display device, including: a display panel; and according to the fingerprint identification structure.

For example, in a display device provided in an embodiment of the present disclosure, the display panel includes a display area and a peripheral area located at a periphery of the display area, and the fingerprint identification structure further includes: a plurality of receiving circuits, the plurality of receiving circuits are respectively electrically connected with the plurality of strip-shaped receiving electrodes, wherein each receiving circuit comprises: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and the strip-shaped receiving electrodes, the first source electrode and the first electrode are connected to a storage node, the signal reading unit is configured to read the electric signals stored in the storage capacitor, the plurality of intersection regions are located in the display region, and orthographic projections of the plurality of receiving circuits on the display panel are located in the peripheral region.

For example, in a display device provided by an embodiment of the present disclosure, the display panel includes a light emitting side, and the fingerprint identification structure is located on the light emitting side of the display panel.

For example, in a display device provided by an embodiment of the present disclosure, the display panel includes a black matrix, and orthographic projections of the stripe-shaped driving electrodes and the stripe-shaped receiving electrodes on the display panel at least partially overlap with the black matrix.

At least one embodiment of the present disclosure provides a driving method of the fingerprint identification structure, where the plurality of strip-shaped driving electrodes are divided into a plurality of strip-shaped driving electrode groups that are sequentially arranged, each strip-shaped driving electrode group includes N strip-shaped driving electrodes, two adjacent strip-shaped driving electrode groups share N-1 strip-shaped driving electrodes, and the driving method includes: sequentially applying driving voltage to the plurality of strip-shaped driving electrode groups to respectively drive the piezoelectric material layers corresponding to the plurality of strip-shaped driving electrode groups to emit ultrasonic waves; and receiving the ultrasonic waves reflected by the fingerprints by using the piezoelectric material layer and outputting corresponding fingerprint electric signals through the strip-shaped receiving electrodes, wherein N is a positive integer greater than or equal to 1.

For example, in a driving method of a fingerprint identification structure provided in an embodiment of the present disclosure, N is a positive integer greater than or equal to 2, each of the stripe-shaped driving electrode groups includes a first stripe-shaped driving electrode and a second stripe-shaped driving electrode, and applying a driving voltage to each of the stripe-shaped driving electrode groups includes: applying a driving voltage to the first strip-shaped driving electrodes at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrodes to emit ultrasonic waves; and applying a driving voltage to the second strip-shaped driving electrodes at a second time point so that the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrodes is delayed from the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrodes, wherein the second time point is delayed from the first time point.

For example, in a driving method of a fingerprint identification structure provided in an embodiment of the present disclosure, N is a positive integer greater than or equal to 3, each of the stripe-shaped driving electrode groups includes a first stripe-shaped driving electrode, a second stripe-shaped driving electrode, and a third stripe-shaped driving electrode, and applying a driving voltage to each of the stripe-shaped driving electrode groups includes: applying a driving voltage to the first strip-shaped driving electrode and the third strip-shaped driving electrode at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrode and the third strip-shaped driving electrode to emit ultrasonic waves; and applying a driving voltage to the second strip-shaped driving electrodes at a second time point so that the phase of the ultrasonic waves emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrodes is delayed from the phase of the ultrasonic waves emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrodes and the third strip-shaped driving electrodes, wherein the second time point is delayed from the first time point.

For example, in a driving method of a fingerprint identification structure provided in an embodiment of the present disclosure, the fingerprint identification structure further includes: a plurality of receiving circuits, the plurality of receiving circuits are respectively electrically connected with the plurality of strip-shaped receiving electrodes, wherein each receiving circuit comprises: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and a signal reading unit, wherein the strip-shaped receiving electrode, the first source electrode and the first pole are connected to a storage node, the signal reading unit is configured to read an electrical signal stored in the storage capacitor, and receiving an ultrasonic wave reflected by a fingerprint by using the piezoelectric material layer and outputting a corresponding fingerprint electrical signal through the strip-shaped receiving electrode includes: when a driving voltage is applied to the strip-shaped driving electrode group to drive the piezoelectric material layer corresponding to the strip-shaped driving electrode group to emit ultrasonic waves, a starting signal is applied to the first grid electrode to open the first thin film transistor; applying bias voltage to the first drain electrode according to the arrival time of the surface echo so as to lift the fingerprint electric signal on the strip-shaped receiving electrode, and storing the lifted fingerprint electric signal in the storage capacitor; and reading out the fingerprint electric signal after lifting by using the signal reading unit.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description relate only to some embodiments of the present disclosure and are not limiting to the present disclosure.

FIG. 1 is a schematic illustration of a fingerprint identification structure transmitting ultrasonic waves;

FIG. 2 is a schematic diagram of a fingerprint identification structure receiving ultrasonic waves;

FIG. 3 is a diagram of a fingerprint identification structure for performing fingerprint identification;

FIG. 4 is a schematic diagram of a fingerprint identification structure;

FIG. 5 is a schematic plan view of a fingerprint identification structure provided according to an embodiment of the present disclosure;

fig. 6A is a schematic diagram illustrating an implementation of ultrasonic focusing by a fingerprint identification structure according to an embodiment of the present disclosure;

fig. 6B is a schematic diagram of another fingerprint identification structure according to an embodiment of the present disclosure for implementing ultrasonic focusing;

fig. 7A is a schematic diagram illustrating an ultrasonic wave emitted from a fingerprint identification structure focused on a valley of a fingerprint according to an embodiment of the present disclosure;

fig. 7B is a schematic diagram of an embodiment of the present disclosure illustrating ultrasonic waves emitted from a fingerprint identification structure focused on ridges of a fingerprint;

FIG. 8 is a schematic plan view of another fingerprint identification structure provided in accordance with an embodiment of the present disclosure;

FIG. 9 is a schematic plan view of another fingerprint identification structure provided in accordance with an embodiment of the present disclosure;

FIG. 10 is a schematic cross-sectional view along the direction AA in FIG. 5 of a fingerprint identification structure according to an embodiment of the present disclosure;

FIG. 11 is a schematic plan view of another fingerprint identification structure provided in accordance with an embodiment of the present disclosure;

FIG. 12 is a schematic diagram of a receiver circuit in a fingerprint identification configuration according to an embodiment of the present disclosure;

fig. 13 is a schematic structural diagram of a display device according to an embodiment of the present disclosure;

fig. 14 is a schematic plan view of a display device according to an embodiment of the present disclosure; and

fig. 15 is a flowchart illustrating a driving method of a fingerprint identification structure according to an embodiment of the present disclosure.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.

Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

FIG. 1 is a schematic illustration of a fingerprint identification structure transmitting ultrasonic waves; FIG. 2 is a schematic diagram of a fingerprint identification structure receiving ultrasonic waves. As shown in fig. 1, the fingerprint recognition structure includes an ultrasonic sensor 10; the ultrasonic sensor 10 includes an upper electrode 11, a lower electrode 12, and a piezoelectric layer 13 located between the upper electrode 11 and the lower electrode 12; the piezoelectric layer 13 is made of a piezoelectric material and can be excited by a voltage to generate an inverse piezoelectric effect. As shown in fig. 1, when an alternating voltage (AC voltage) is input to the upper electrode 11 and the lower electrode 12 (for example, the upper electrode 11 is grounded, and an AC square wave is applied to the lower electrode 12), the piezoelectric layer 13 is deformed due to the inverse piezoelectric effect or the film layers above and below the piezoelectric layer 13 are driven to vibrate together, so that ultrasonic waves can be generated and emitted outwards. It should be noted that when a cavity (e.g., an air cavity) is provided on a side of the upper electrode 11 away from the piezoelectric layer 13 or a side of the lower electrode 12 away from the piezoelectric layer 13, the ultrasonic wave emitted from the ultrasonic sensor is strengthened, so that the ultrasonic wave can be better emitted.

As shown in fig. 2, the ultrasonic wave emitted from the ultrasonic sensor 10 is reflected by the fingerprint 500, and the reflected ultrasonic wave is converted into an alternating voltage on the piezoelectric layer; at this time, the upper electrode 11 is grounded, and the lower electrode 12 can be used as a receiving electrode to receive the alternating voltage generated by the piezoelectric layer. Since the fingerprint 500 includes the valleys 510 and the ridges 520, they have different reflection abilities with respect to the ultrasonic waves (the valleys 510 have a stronger reflection ability with respect to the ultrasonic waves), resulting in different intensities of the ultrasonic waves reflected back by the valleys 510 and the ridges 520. Therefore, whether the ultrasonic wave is an ultrasonic wave reflected by a valley or a ridge can be judged by the alternating voltage received by the receiving electrode.

Fig. 3 is a schematic diagram of a fingerprint identification structure for performing fingerprint identification. As shown in fig. 3, the fingerprint identification structure includes an upper electrode 11, a plurality of lower electrodes 12, a piezoelectric layer 13 located between the upper electrode 11 and the plurality of lower electrodes 12, a substrate 80 located on a side of the upper electrode 11 away from the piezoelectric layer 13, and a protective layer 90 located on a side of the plurality of lower electrodes 12 away from the piezoelectric layer 13; the ultrasonic sensor 10 composed of the lower electrode 12, the piezoelectric layer 13 and the plurality of upper electrodes 11 can transmit and receive ultrasonic waves, that is, the ultrasonic sensor 10 functions as both an ultrasonic transmitting sensor and an ultrasonic receiving sensor. When the fingerprint is contacted with the substrate 80, the ultrasonic wave emitted by the ultrasonic sensor 10 is reflected by the fingerprint 500, and the reflected ultrasonic wave is converted into an alternating voltage on the piezoelectric layer; at this time, the upper electrode 11 is grounded, and the plurality of lower electrodes 12 can be used as receiving electrodes, so that the alternating voltages generated by the piezoelectric layers can be received at different positions. Since the fingerprint 500 includes the valleys 510 and the ridges 520, they have different reflection abilities with respect to the ultrasonic waves (the valleys 510 have a stronger reflection ability with respect to the ultrasonic waves), resulting in different intensities of the ultrasonic waves reflected back by the valleys 510 and the ridges 520. Therefore, the position information of the valleys and ridges in the fingerprint 500 can be obtained by the alternating voltages received by the plurality of lower electrodes 12, so that fingerprint recognition can be realized.

Fig. 4 is a schematic structural diagram of a fingerprint identification structure. As shown in fig. 4, the upper electrode 11, the lower electrode 12 and the piezoelectric layer 13 can be formed on the same side of the thin film transistor substrate 91. The fingerprint identification structure further comprises: bias resistor 60 and bonding pad 70; bias resistor 60 may be used to calibrate the voltage and bond pad 70 may be used to bond the external circuit.

At present, in order to realize fingerprint identification, a typical fingerprint identification structure includes a plurality of block-shaped receiving electrodes (upper electrodes or lower electrodes) arranged in an array, and each block-shaped receiving electrode needs to be provided with a receiving circuit correspondingly to receive and process a voltage signal received by each receiving electrode. And the receiving circuit generally includes a multilayer structure of a thin film transistor and a capacitor. On one hand, the fingerprint identification structure has more film layers (at least comprising an upper electrode, a lower electrode, a piezoelectric layer and a multilayer structure of a receiving circuit), so that the light transmittance is low, and the fingerprint identification structure can only be arranged below a display panel, thereby causing high power consumption; on the other hand, the fingerprint identification structure is complex in structure and high in cost.

The embodiment of the disclosure provides a fingerprint identification structure, a driving method of the fingerprint identification structure and a display device. The fingerprint identification structure comprises a first electrode layer, a piezoelectric material layer and a second electrode layer; the first electrode layer comprises a plurality of strip-shaped receiving electrodes arranged at intervals; the piezoelectric material layer is arranged on one side of the first electrode layer; the second electrode layer is arranged on one side, far away from the first electrode layer, of the piezoelectric material layer and comprises a plurality of strip-shaped driving electrodes arranged at intervals, each strip-shaped driving electrode extends along a first direction, each strip-shaped receiving electrode extends along a second direction, the first direction and the second direction are intersected, the strip-shaped driving electrodes and the strip-shaped receiving electrodes are intersected with each other to form a plurality of intersection regions, and the piezoelectric material layer is at least overlapped with the intersection regions. In each intersection region, the strip-shaped drive electrodes, the strip-shaped receiving electrodes, and the piezoelectric material layer form an ultrasonic sensor. Therefore, the fingerprint identification structure can respectively realize the transmission and the reception of ultrasonic waves by utilizing the plurality of strip driving electrodes, the plurality of strip receiving electrodes and the piezoelectric material layer in a scanning driving mode, and a receiving circuit is not required to be arranged in each cross area, so that the number of film layers in the fingerprint identification structure can be reduced to improve the light transmittance of the fingerprint identification structure, the fingerprint identification structure can be arranged on the display panel, and the power consumption of the fingerprint identification structure can be reduced. In addition, the fingerprint identification structure is simple in structure and low in cost. On the other hand, the fingerprint identification structure can also realize the focusing (mutual interference) of ultrasonic waves by respectively driving the strip-shaped driving electrodes, so that the intensity or energy of the emitted ultrasonic waves in a specific area can be improved, the fingerprint identification performance is improved, the emitted ultrasonic waves can have better directivity, the crosstalk between valleys and ridges of fingerprints can be reduced, and the fingerprint identification performance can be improved.

The fingerprint identification structure, the driving method of the fingerprint identification structure, and the display device provided in the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

An embodiment of the present disclosure provides a fingerprint identification structure. Fig. 5 is a schematic plan view of a fingerprint identification structure according to an embodiment of the present disclosure. As shown in fig. 5, the fingerprint identification structure 100 includes a first electrode layer 110, a piezoelectric material layer 130, and a second electrode layer 120; the first electrode layer 110 includes a plurality of strip-shaped receiving electrodes 112 disposed at intervals, for example, the plurality of strip-shaped receiving electrodes 112 may be parallel to each other; the piezoelectric material layer 130 is disposed at one side of the first electrode layer 110; the second electrode layer 120 is disposed on a side of the piezoelectric material layer 130 away from the first electrode layer 110, that is, the piezoelectric material layer 130 is located between the first electrode layer 110 and the second electrode layer 120; the second electrode layer 120 includes a plurality of strip-shaped driving electrodes 122 disposed at intervals, for example, the plurality of strip-shaped driving electrodes 122 may be parallel to each other; each of the stripe-shaped driving electrodes 122 extends along a first direction, each of the stripe-shaped receiving electrodes 112 extends along a second direction, the first direction and the second direction intersect, for example, the first direction and the second direction may be perpendicular to each other, the plurality of stripe-shaped driving electrodes 122 and the plurality of stripe-shaped receiving electrodes 112 intersect with each other to form a plurality of intersection regions 140, and the piezoelectric material layer 130 overlaps at least the plurality of intersection regions 140. It should be noted that a plurality of intersection regions 140 are formed by one strip-shaped receiving electrode 112 and a plurality of strip-shaped driving electrodes 122; in addition, the above-mentioned "the piezoelectric material layer overlaps at least the plurality of intersection regions" means that the piezoelectric material layer falls within the plurality of intersection regions; that is, the piezoelectric material layer includes portions located at the plurality of intersection regions, and may also include portions located outside the plurality of intersection regions.

In the fingerprint identification structure provided in the present embodiment, the strip-shaped driving electrodes 122, the strip-shaped receiving electrodes 112, and the piezoelectric material layer 130 form an ultrasonic sensor in each intersection area 140. When the fingerprint identification structure is used for fingerprint identification, the strip-shaped receiving electrode 112 can be grounded, then an alternating voltage is applied to one of the strip-shaped driving electrodes 122, the piezoelectric material layer 130 corresponding to the strip-shaped driving electrode 122 can deform due to the inverse piezoelectric effect or drive the film layers above and below the piezoelectric material layer 130 to vibrate together, and thus ultrasonic waves can be generated and emitted outwards; when the emitted ultrasonic waves are reflected back to the fingerprint identification structure by the fingerprint, the multiple intersection regions 140 corresponding to the multiple strip-shaped receiving electrodes 112 and the strip-shaped driving electrodes 122 can receive the reflected ultrasonic waves, and can convert ultrasonic signals received by the multiple intersection regions 140 corresponding to the strip-shaped driving electrodes 122 into electric signals, and output the electric signals through the multiple strip-shaped receiving electrodes 112 respectively, and at this time, the electric signals output by the multiple strip-shaped receiving electrodes 112 are reflected echo information corresponding to the strip-shaped driving electrodes 122; after the ac square waves are applied to the plurality of strip-shaped driving electrodes 122 respectively to perform ultrasonic transmission and reception, the reflected echo information corresponding to the entire fingerprint identification structure can be obtained, thereby realizing fingerprint identification. Therefore, the fingerprint identification structure can respectively realize the transmission and the reception of ultrasonic waves by utilizing the plurality of strip-shaped driving electrodes, the plurality of strip-shaped receiving electrodes and the piezoelectric material layer in a scanning driving mode. Therefore, the fingerprint identification structure does not need to be provided with a receiving circuit in each intersection area, so that the quantity of the film layers in the fingerprint identification structure can be reduced to improve the light transmittance of the fingerprint identification structure, the fingerprint identification structure can be arranged on a display panel, and the power consumption of the fingerprint identification structure can be reduced. In addition, the fingerprint identification structure is simple in structure and low in cost.

On the other hand, the fingerprint identification structure can also realize the focusing (mutual interference) of ultrasonic waves by respectively driving the strip-shaped driving electrodes, so that the intensity or energy of the emitted ultrasonic waves in a specific area can be improved, the fingerprint identification performance is improved, the emitted ultrasonic waves can have better directivity, the crosstalk between valleys and ridges of fingerprints can be reduced, and the fingerprint identification performance can be improved. When the fingerprint identification structure improves the intensity or energy of the emitted ultrasonic waves in a specific area or a specific direction by realizing the focusing (increasing interference) of the ultrasonic waves, the fingerprint identification structure not only can realize fingerprint identification, but also can penetrate through a finger to distinguish whether the fingerprint is real skin or not.

For example, the width of the strip-shaped driving electrodes may be in the range of 50-70 microns, and the width of the strip-shaped receiving electrodes may be in the range of 50-70 microns. The width of the space between two adjacent strip-shaped driving electrodes is also in the range of 50-70 microns, and the width of the space between two adjacent strip-shaped receiving electrodes is also in the range of 50-70 microns.

Fig. 6A is a schematic diagram of a fingerprint identification structure according to an embodiment of the present disclosure for implementing ultrasonic focusing. Fig. 6A shows an example of the fingerprint identification structure implementing ultrasonic focusing. As shown in fig. 6A, the plurality of stripe-shaped driving electrodes 122 includes a first stripe-shaped driving electrode 1221 and a second stripe-shaped driving electrode 1222. At this time, a driving voltage (e.g., an alternating voltage) is applied to the first strip-shaped driving electrodes 1221 at a first time point to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrodes 1221 to emit ultrasonic waves, then a driving voltage is applied to the second strip driving electrodes 1222 at a second time point to delay the phase of the ultrasonic wave emitted from the piezoelectric material layer corresponding to the second strip driving electrodes 1222 from the phase of the ultrasonic wave emitted from the piezoelectric material layer corresponding to the first strip driving electrodes 1221, so that focusing of the ultrasonic waves (constructive interference) can be achieved directly above the second strip driving electrodes 1222 (or at other positions of the second strip driving electrodes 1222 far from the first strip driving electrodes 1221), that is, the intensity or energy of the ultrasonic wave directly above the second strip-shaped driving electrode 1222 is enhanced, so that the fingerprint identification structure not only can realize fingerprint identification, but also can penetrate through a finger to distinguish whether the fingerprint is real skin. It should be noted that the second time point is delayed from the first time point. It should be noted that, the delay amount between the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrode and the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrode can be obtained through testing according to actual situations.

Fig. 6B is a schematic diagram of another fingerprint identification structure according to an embodiment of the present disclosure for implementing ultrasonic focusing. FIG. 6B illustrates another example of the fingerprint identification structure implementing ultrasonic focusing. As shown in fig. 6B, the plurality of stripe-shaped driving electrodes 122 includes a first stripe-shaped driving electrode 1221, a second stripe-shaped driving electrode 1222, and a third stripe-shaped driving electrode 1223. At this time, a driving voltage is applied to the first strip-shaped driving electrode 1221 and the third strip-shaped driving electrode 1223 at a first time point to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrode 1221 and the third strip-shaped driving electrode 1223 to emit ultrasonic waves; and applying a driving voltage to the second strip driving electrodes 1222 at a second time point to delay the phase of the ultrasonic wave emitted from the piezoelectric material layer corresponding to the second strip driving electrodes 1222 from the phase of the ultrasonic wave emitted from the piezoelectric material layer corresponding to the first strip driving electrodes 1221 and the third strip driving electrodes 1223, so that the focusing (phase-increase interference) of the ultrasonic wave can be realized right above the second strip driving electrodes 1222, that is, the intensity or energy of the ultrasonic wave right above the second strip driving electrodes 1222 is enhanced, so that the fingerprint identification structure can not only realize fingerprint identification, but also penetrate a finger to distinguish whether the fingerprint is true skin.

For example, as shown in fig. 6A and 6B, two or more strip-shaped drive electrodes are driven separately to emit ultrasonic waves, and the ultrasonic waves are focused directly above the strip-shaped drive electrodes that are delay-driven. The ultrasonic receiving element formed by the strip-shaped receiving electrodes can receive the reflected echo, and the electric signals output by the strip-shaped receiving electrodes are the reflected echo information corresponding to the strip-shaped driving electrodes driven in a delayed mode.

It should be noted that, when the plurality of stripe-shaped driving electrodes are driven by the method shown in fig. 6A or fig. 6B, 2 or more stripe-shaped driving electrodes may be used as a group of stripe-shaped driving electrode groups, and the delay driving may be performed in each stripe-shaped driving electrode group according to the method shown in fig. 6A or fig. 6B, but different stripe-shaped driving electrode groups are driven separately, for example, by scanning.

Fig. 7A is a schematic diagram illustrating an ultrasonic wave emitted from a fingerprint identification structure focused on a valley of a fingerprint according to an embodiment of the present disclosure; fig. 7B is a schematic diagram of an embodiment of the present disclosure, in which ultrasonic waves emitted from a fingerprint identification structure are focused on ridges of a fingerprint.

As shown in fig. 7A, when the ultrasonic waves emitted from the fingerprint identification structure are focused on the valleys 510 of the fingerprint 500, the energy or intensity of the ultrasonic waves reflected by the valleys 510 is greater; as shown in fig. 7B, when the ultrasonic waves emitted from the fingerprint identification structure are focused on the ridge 520 of the fingerprint 500, the energy or intensity of the ultrasonic waves reflected by the ridge 520 is smaller. Accordingly, the difference between the intensity and energy of the ultrasonic waves reflected by the valleys 510 and the ridges 520 of the fingerprint 500 is also greater, thereby contributing to an improvement in fingerprint recognition performance. On the other hand, as shown in fig. 7A and 7B, the ultrasonic waves emitted by the fingerprint identification structure have better directivity, so that the crosstalk between the valleys and the ridges of the fingerprint can be reduced, and the fingerprint identification performance can be improved.

For example, in some examples, the piezoelectric material layer 130 is not an entire layer structure, but includes sub piezoelectric material layers 132 arranged at intervals, and each sub piezoelectric material layer 132 extends along the first direction or the second direction, so that mutual crosstalk between the ultrasonic sensors corresponding to different intersection regions can be reduced. Fig. 8 is a schematic plan view of another fingerprint identification structure provided according to an embodiment of the present disclosure. As shown in fig. 8, the piezoelectric material layer 130 includes sub piezoelectric material layers 132 arranged at intervals, and each sub piezoelectric material layer 132 extends in the second direction. That is, the plurality of sub-piezoelectric material layers 132 are disposed in one-to-one correspondence with the plurality of strip-shaped receiving electrodes 112. Of course, the plurality of sub-piezoelectric material layers may also extend in the first direction and be disposed in one-to-one correspondence with the plurality of strip-shaped driving electrodes.

Fig. 9 is a schematic plan view of another fingerprint identification structure provided according to an embodiment of the present disclosure. As shown in fig. 9, the piezoelectric material layer 130 includes a plurality of sub-piezoelectric material blocks 134, and the plurality of sub-piezoelectric material blocks 134 are disposed in one-to-one correspondence with the plurality of intersection regions 140, so that mutual crosstalk between the ultrasonic sensors corresponding to different intersection regions can be further reduced.

Note that when the piezoelectric material layers adopt the structure shown in fig. 8 or 9, the spaces between different pieces of piezoelectric sub-material layers or the spaces between different pieces of piezoelectric sub-material may be filled with an insulating material such as resin. For example, the spaces between different pieces of piezoelectric sub-material or the spaces between different pieces of piezoelectric sub-material may also be filled with an elastic insulating material to facilitate vibration of the piezoelectric material layers corresponding to the crossover regions.

Fig. 10 is a schematic cross-sectional view along the direction AA in fig. 5 illustrating a fingerprint identification structure according to an embodiment of the present disclosure. As shown in fig. 10, the second electrode layer 120 further includes a retaining wall 124 located between two adjacent strip-shaped driving electrodes 122. In order to make the fingerprint identification structure 100 have high receiving sensitivity to ultrasonic waves, the piezoelectric material layer 130 is usually made of piezoelectric material with a high piezoelectric voltage constant, such as PVDF (polyvinylidene fluoride); piezoelectric materials with higher piezoelectric voltage constants such as PVDF (polyvinylidene fluoride) require higher driving voltages to generate ultrasonic waves with higher intensity. The second electrode layer 120 needs to be made thicker, for example, more than 10 microns, in order to be suitable for carrying higher voltages. Through the retaining wall 124, a patterned metal layer may be formed on the side of the piezoelectric material layer 130 away from the first electrode layer 110, and the metal layer does not need to be made thicker; a metal layer is then electroplated on the patterned metal layer using the dam walls 124 and an electroplating process, thereby obtaining a thicker second electrode layer. It should be noted that, in the electroplating process, under the action of the electric field, the metal layer can continue to grow only on the patterned metal layer, and the retaining wall can play a role in separation, so as to prevent the electroplated metal layers from being connected with each other.

For example, in some examples, the piezoelectric material layer 130 may also be made of piezoelectric materials such as ALN (aluminum nitride), PZT (lead zirconate titanate piezoelectric ceramic), and the like. For example, the piezoelectric material layer may be fabricated by a sol-gel method.

For example, in some examples, as shown in fig. 10, each of the stripe-shaped driving electrodes 122 may include a first sub driving electrode 1291 and a second sub driving electrode 1292 which are stacked, and each of the first sub driving electrode 1291 and the second sub driving electrode 1292 is also a stripe-shaped sub electrode extending in the first direction. The first sub driving electrode 1291 may be a metal layer formed using a patterning process, and the second sub driving electrode 1292 may be a metal layer formed using a plating process.

For example, in some examples, the size of the dam 124 in a direction perpendicular to the piezoelectric material layer 130 ranges from 1 to 20 micrometers, and the size of the second electrode layer 120 in a direction perpendicular to the piezoelectric material layer 130 ranges from 1 to 20 micrometers. Because the thickness of the second electrode layer 120 is thick, the resistance of the second electrode layer 120 is small, and the uniformity of the surface is good, so that good electrical performance (for example, high driving voltage is loaded) can be realized, uniform reflection of ultrasonic waves can also be realized, and identification of valleys and ridges of fingerprints is facilitated.

For example, in some examples, the material of the strip-shaped drive electrodes includes one or more of copper, silver, and aluminum. The material of the strip-shaped receiving electrode may also comprise one or more of copper, silver and aluminum.

For example, the retaining wall 124 may be made of a resin material, which may have a lower cost and a lower manufacturing difficulty.

For example, in some examples, as shown in fig. 10, the fingerprint identification structure 100 further includes: the substrate 180 is located on a side of the first electrode layer 110 away from the piezoelectric material layer 130, and includes a contact surface 181 configured to contact a fingerprint. When a fingerprint contacts the contact surface 181, the fingerprint identification structure 100 may identify the fingerprint by emitting ultrasonic waves to the fingerprint and receiving ultrasonic waves (echoes) reflected by the fingerprint 500. Of course, the embodiments of the present disclosure include, but are not limited to, when the fingerprint identification structure 100 is used in a display device, the substrate 180 may be a cover plate of the display device.

For example, in some examples, the substrate 180 comprises a glass substrate.

For example, in some examples, the substrate 180 comprises a polyimide substrate. Thus, the substrate 180 can be made thin, with the thickness of the substrate 180 ranging from 5-20 microns. When the substrate 180 is a polyimide substrate, a polyimide layer may be formed on a glass substrate, and then a first electrode layer, a piezoelectric material layer, a second electrode layer, and other layer structures are formed on the polyimide layer, and finally the glass substrate is removed, so as to obtain the fingerprint identification structure described in this example.

For example, in some examples, as shown in fig. 10, the fingerprint identification structure 100 further includes: and the protective layer 190 is located on the side of the second electrode layer 120 away from the piezoelectric material layer 130. The protection layer 190 can protect the strip-shaped driving electrodes 122 in the second electrode layer 120. For example, the material of the protective layer 190 may be epoxy resin.

Fig. 11 is a schematic plan view of a fingerprint identification structure according to an embodiment of the present disclosure. As shown in fig. 11, the fingerprint identification structure 100 further includes a plurality of receiving circuits 150, the plurality of receiving circuits 150 are electrically connected to the plurality of strip-shaped receiving electrodes 112, respectively, the fingerprint identification structure 100 includes an effective identification area 101 and a rim area 102 located at the periphery of the effective identification area 101, a plurality of intersection areas 130 are located in the effective identification area 101, and a plurality of receiving circuits 150 are located in the rim area 102. At this time, one strip-shaped receiving electrode 112 corresponding to the plurality of crossing regions 130 is connected to only one receiving circuit 150, and there is no need to provide one receiving circuit 150 in each crossing region 130, so that the number of film layers of the fingerprint identification structure can be greatly reduced, and the structure of the fingerprint identification structure can be simplified. It should be noted that, the effective identification area is an area where the fingerprint identification structure can perform fingerprint identification; when the fingerprint is in the effective identification area, the fingerprint identification structure can identify the fingerprint; whereas the edge area cannot be fingerprinted.

Fig. 12 is a schematic diagram of a receiving circuit according to an embodiment of the disclosure. As shown in fig. 12, the receiving circuit 150 includes a storage capacitor 151, a first thin film transistor 152, and a signal reading unit 153. The storage capacitor 151 includes a first pole 1511 and a second pole 1512; the first thin film transistor 152 includes a first gate 1521, a first source 1522, and a first drain 1523; the strip receiving electrode 112, the first source 1522 and the first pole 1511 are connected to the storage node 154, so that the fingerprint electrical signal received by the strip receiving electrode 112 can be stored in the storage capacitor 151, and the signal reading unit 153 is configured to read the fingerprint electrical signal (electrical signal) stored in the storage capacitor 151, i.e. the voltage signal received by the strip receiving electrode 112. In addition, in the process of storing the fingerprint electrical signal received by the strip-shaped receiving electrode 112 in the storage capacitor 151, a bias voltage may be applied to the first drain electrode 1523, so that the alternating voltage received by the receiving electrode 112 is raised, and a detection signal with a relatively high contrast is obtained.

For example, in some examples, the first thin film transistor 152 is an oxide thin film transistor, such as an Indium Gallium Zinc Oxide (IGZO) thin film transistor. After the fingerprint electrical signal received by the strip-shaped receiving electrode 112 is stored in the storage capacitor 151, the voltage of the storage node 154 is inputted from the piezoelectric structure and the first thin film transistor corresponding to the strip-shaped receiving electrode 112Line leakage due to leakage current of the order of 10 for the piezoelectric structure^-15A, the leakage current magnitude of the low-temperature polycrystalline silicon thin film transistor is 10^-12A, the leakage current of oxide thin film transistor, such as IGZO thin film transistor, is 10^-15When the first thin film transistor 152 is an oxide thin film transistor, the overall leakage current of the driving circuit can be reduced, thereby ensuring the stability of the fingerprint electrical signal on the storage node 154 and improving the fingerprint identification performance of the fingerprint identification structure.

For example, in some examples, the signal reading unit 153 includes: a second thin film transistor 155 and a third thin film transistor 156; the second thin film transistor 155 includes a second gate electrode 1551, a second source electrode 1552, and a second drain electrode 1553; the third thin film transistor 156 includes a third gate electrode 1561, a third source electrode 1562, and a third drain electrode 1563. The second gate electrode 1551 is connected to the storage node 154, the second drain electrode 1553 is connected to the third source electrode 1562, the second source electrode 1552 is configured to apply a fixed voltage, the third gate electrode 1561 is configured to apply a readout instruction signal, and the third drain electrode 1563 is configured to output a signal, so that a detection signal (electric signal) stored in the storage capacitor 151 can be read.

An embodiment of the present disclosure also provides a display device. Fig. 13 is a schematic structural diagram of a display device according to an embodiment of the present disclosure. The display device comprises a display module 200 and the fingerprint identification structure 100 provided by the above embodiment. Because this fingerprint identification structure can utilize a plurality of strip drive electrodes, ultrasonic wave's transmission and receipt are realized respectively through the scanning drive mode to a plurality of strip receiving electrodes and piezoelectric material layer, need not set up receiving circuit at every intersection region, consequently the quantity of rete is in order to improve this fingerprint identification structure's light transmissivity in reducible this fingerprint identification structure, consequently this display device can set up this fingerprint identification structure in display panel's luminous side, and then can reduce this fingerprint identification structure's consumption, and then reduce whole display device's consumption, and prolong the time of endurance. In addition, the fingerprint identification structure is simple in structure, so that the cost of the display device is low. On the other hand, the display device can also realize the focusing (mutual interference) of the ultrasonic waves by respectively driving the strip-shaped driving electrodes, so that the intensity or energy of the emitted ultrasonic waves in a specific area can be improved, the fingerprint identification performance is improved, the emitted ultrasonic waves have better directivity, the crosstalk between valleys and ridges of the fingerprint can be reduced, and the fingerprint identification performance can be improved. When the fingerprint identification structure improves the intensity or energy of the emitted ultrasonic waves in a specific area or a specific direction by realizing the focusing (increasing interference) of the ultrasonic waves, the fingerprint identification structure not only can realize fingerprint identification, but also can penetrate through a finger to distinguish whether the fingerprint is real skin or not. For details, reference may be made to the description of the above embodiments, which are not repeated herein.

For example, in some examples, the display module 200 includes a light emitting side 220, and the fingerprint recognition structure 100 is located on the light emitting side 220 of the display module 200.

For example, in some examples, the display module 200 is an Organic Light Emitting Diode (OLED) display module. As shown in fig. 13, the display module 200 includes a thin film transistor 250, an anode 260, a light emitting layer 270, and a cathode 280. The thin film transistor 250 includes a drain electrode 253, an anode 260 electrically connected to the drain electrode 253, and a light emitting layer 270 disposed between the anode 260 and a cathode 280.

For example, the thin film transistor 250 further includes a gate electrode 251, a source electrode 252, and an active layer 254.

For example, in some examples, the display module 200 includes the black matrix or pixel defining layer 230, and the orthographic projection of the strip-shaped driving electrodes 122 and the strip-shaped receiving electrodes 112 on the display module 200 at least partially overlaps the black matrix or pixel defining layer 230.

Fig. 14 is a schematic plan view of a display device according to an embodiment of the disclosure. As shown in fig. 14, the display module 200 includes a display area 201 and a peripheral area 202 located in the display area 201, and the fingerprint identification structure 100 further includes: a plurality of receiving circuit, a plurality of receiving circuit respectively with a plurality of strip receiving electrode electrical property link to each other, each receiving circuit includes: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and a signal reading unit, the strip-shaped receiving electrode, the first source electrode and the first pole are connected to the storage node, and the signal reading unit is configured to read the electrical signal stored in the storage capacitor. As shown in fig. 14, the plurality of intersection regions 130 are located in the display region 201, and the orthographic projections of the plurality of receiving circuits 150 on the display module 200 are located in the peripheral region 202. The display area 201 is used for displaying a picture, and the peripheral area 202 does not display the picture. Therefore, the intersection region 130 has only three film layers (the strip-shaped driving electrode, the piezoelectric material layer and the strip-shaped receiving electrode) and has high light transmittance, so that the intersection region 130 is arranged in the display region 201, and the influence on the display is small, and the power of the fingerprint identification structure can be reduced, so that the power consumption of the fingerprint identification structure is reduced. The receiving circuit has more film layers and smaller transmittance, and the display cannot be influenced by arranging the receiving circuit in the peripheral area. Therefore, the display device provided by this example can achieve both good light transmittance and good electrical signal quality. Of course, the disclosure includes but is not limited thereto, the fingerprint identification structure may also be completely disposed at the peripheral region of the display panel. It should be noted that the structure and position of the receiving circuit can be referred to the related description of fig. 11 and fig. 12.

For example, the display device may be an electronic device having a display function, such as a television, a mobile phone, a computer, a notebook computer, an electronic album, and a navigator.

An embodiment of the present disclosure further provides a driving method of the fingerprint identification structure. Fig. 15 illustrates a driving method of a fingerprint identification structure according to an embodiment of the present disclosure. In the fingerprint identification structure, a plurality of strip-shaped driving electrodes are divided into a plurality of strip-shaped driving electrode groups which are sequentially arranged, each strip-shaped driving electrode group comprises N strip-shaped driving electrodes, two adjacent strip-shaped driving electrode groups share N-1 strip-shaped driving electrodes, and N is a positive integer greater than or equal to 1. As shown in fig. 15, the driving method of fingerprint recognition includes the following steps S301 to S302.

Step S301: and sequentially applying driving voltage to the strip-shaped driving electrode groups to respectively drive the piezoelectric material layers corresponding to the strip-shaped driving electrode groups to emit ultrasonic waves.

For example, an alternating voltage may be applied to a plurality of strip-like drive electrode groups in sequence.

Step S302: and receiving the ultrasonic waves reflected by the fingerprints by using the piezoelectric material layer and outputting corresponding fingerprint electric signals through the strip-shaped receiving electrodes.

In the driving method of the fingerprint identification structure provided in this embodiment, the plurality of strip-shaped driving electrodes are divided into a plurality of strip-shaped driving electrode groups that are sequentially arranged, each strip-shaped driving electrode group includes N strip-shaped driving electrodes, two adjacent strip-shaped driving electrode groups share N-1 strip-shaped driving electrodes, and N is a positive integer greater than or equal to 1. When N is 1, each strip-shaped driving electrode group comprises one strip-shaped driving electrode; when N is larger than or equal to 2, each strip-shaped driving electrode group comprises at least two strip-shaped driving electrodes. In the driving method, the driving voltage is sequentially applied to the plurality of strip-shaped driving electrode groups to respectively drive the piezoelectric material layers corresponding to the plurality of strip-shaped driving electrode groups to emit ultrasonic waves, so that the plurality of strip-shaped driving electrode groups can be prevented from simultaneously driving the piezoelectric material layers to emit the ultrasonic waves, and the plurality of strip-shaped receiving electrodes can be used for respectively receiving the reflected echoes corresponding to the plurality of strip-shaped driving electrode groups. Therefore, the driving method of the fingerprint identification structure can respectively realize the transmission and the reception of ultrasonic waves by utilizing the plurality of strip-shaped driving electrodes, the plurality of strip-shaped receiving electrodes and the piezoelectric material layer in a scanning driving mode. Therefore, the driving method of the fingerprint identification structure does not need to receive the reflection echo in each intersection area, so that the number of film layers in the fingerprint identification structure can be reduced to improve the light transmittance of the fingerprint identification structure, the fingerprint identification structure can be arranged on a display panel, and the power consumption of the fingerprint identification structure can be reduced.

For example, in some examples, N is a positive integer greater than or equal to 2, each of the strip driving electrode groups includes a first strip driving electrode and a second strip driving electrode, and applying the driving voltage to each of the strip driving electrode groups includes: applying a driving voltage to the first strip-shaped driving electrodes at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrodes to emit ultrasonic waves; and applying a driving voltage to the second strip-shaped driving electrodes at a second time point so that the phase delay of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the second strip-shaped driving electrodes is later than the phase delay of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the first strip-shaped driving electrodes, wherein the second time point is later than the first time point.

Therefore, when the driving method of the fingerprint identification structure applies driving voltage to each strip-shaped driving electrode group to respectively drive the piezoelectric material layers corresponding to the strip-shaped driving electrode groups to emit ultrasonic waves, the focusing (mutual interference) of the ultrasonic waves can be realized by delaying and driving the second strip-shaped driving electrodes in the strip-shaped driving electrode groups, so that the intensity or energy of the emitted ultrasonic waves in a specific area can be improved, the fingerprint identification performance is improved, the emitted ultrasonic waves can have better directivity, the crosstalk between valleys and ridges of fingerprints can be reduced, and the fingerprint identification performance can be improved. When the fingerprint identification structure improves the intensity or energy of the emitted ultrasonic waves in a specific area or a specific direction by realizing the focusing (increasing interference) of the ultrasonic waves, the fingerprint identification structure not only can realize fingerprint identification, but also can penetrate through a finger to distinguish whether the fingerprint is real skin or not. It should be noted that, the delay amount between the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrode and the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrode can be obtained through testing according to actual situations. The specific ultrasonic focusing process can be seen in the related description of fig. 6A.

For example, in some examples, after driving the piezoelectric material layer corresponding to each strip-shaped driving electrode group to emit ultrasonic waves, the reflected echoes are received by the piezoelectric material layer, and then electric signals are output through the plurality of strip-shaped receiving electrodes.

For example, in some examples, N is a positive integer greater than or equal to 3, each of the bar drive electrode groups includes a first bar drive electrode, a second bar drive electrode, and a third bar drive electrode, and applying the drive voltage to each of the bar drive electrode groups includes: applying a driving voltage to the first strip-shaped driving electrode and the third strip-shaped driving electrode at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrode and the third strip-shaped driving electrode to emit ultrasonic waves; and applying a driving voltage to the second strip-shaped driving electrodes at a second time point so that the phase delay of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the second strip-shaped driving electrodes is longer than the phase delay of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the first strip-shaped driving electrodes and the third strip-shaped driving electrodes, and the second time point is longer than the first time point.

Therefore, when the driving method of the fingerprint identification structure applies driving voltage to each strip-shaped driving electrode group to respectively drive the piezoelectric material layers corresponding to the strip-shaped driving electrode groups to emit ultrasonic waves, the first strip-shaped driving electrode and the third strip-shaped driving electrode in the strip-shaped driving electrode groups are driven firstly, and the second strip-shaped driving electrode in the strip-shaped driving electrode groups is driven in a delayed mode to realize focusing (phase-increase interference) of the ultrasonic waves, so that the strength or energy of the emitted ultrasonic waves in a specific area can be improved, the fingerprint identification performance is improved, the emitted ultrasonic waves can have good directivity, crosstalk between valleys and ridges of fingerprints can be reduced, and the fingerprint identification performance can be improved. When the fingerprint identification structure improves the intensity or energy of the emitted ultrasonic waves in a specific area or a specific direction by realizing the focusing (increasing interference) of the ultrasonic waves, the fingerprint identification structure not only can realize fingerprint identification, but also can penetrate through a finger to distinguish whether the fingerprint is real skin or not. It should be noted that, the delay amount between the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrode and the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrode and the third strip-shaped driving electrode can be obtained by testing according to actual situations. The specific ultrasonic focusing process can be seen in the related description of fig. 6B.

For example, in some examples, the fingerprint identification structure further comprises: a plurality of receiving circuit, a plurality of receiving circuit respectively with a plurality of strip receiving electrode electric property link to each other, wherein, each receiving circuit includes: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and a signal reading unit, wherein the strip-shaped receiving electrode, the first source electrode and the first pole are connected to the storage node, the signal reading unit is configured to read the electric signals stored in the storage capacitor, and the signal reading unit receives the ultrasonic waves reflected by the fingerprint by using the piezoelectric material layer and outputs corresponding fingerprint electric signals through the strip-shaped receiving electrode comprises: when a driving voltage is applied to the strip-shaped driving electrode group to drive the piezoelectric material layer corresponding to the strip-shaped driving electrode group to emit ultrasonic waves, a starting signal is applied to the first grid electrode to open the first thin film transistor so as to eliminate aftershock; applying bias voltage to the first drain electrode according to the arrival time of the surface echo so as to lift the fingerprint electric signal on the strip-shaped receiving electrode, and storing the lifted fingerprint electric signal in a storage capacitor; and reading out the lifted fingerprint electric signal by using a signal reading unit.

For example, in some examples, to reduce noise signals, when a fingerprint does not touch the fingerprint identification structure, ultrasonic waves may be transmitted and reflected echoes may be received to obtain a base value; then when the fingerprint touches the fingerprint identification structure, transmitting ultrasonic waves and receiving reflected echoes to obtain a fingerprint electric signal; the fingerprint electrical signal is subtracted from the reference value to remove the noise effect.

An embodiment of the present disclosure further provides a manufacturing method of the fingerprint identification structure. The manufacturing method comprises the following steps: providing a substrate base plate; forming a first electrode layer on one side of a substrate, wherein the first electrode layer comprises a plurality of receiving driving electrodes arranged at intervals; forming a piezoelectric material layer on one side of the first electrode layer, which is far away from the substrate base plate; and forming a second electrode layer on one side of the piezoelectric material layer, which is far away from the first electrode layer, wherein the second electrode layer comprises a plurality of strip-shaped driving electrodes arranged at intervals, each strip-shaped driving electrode extends along a first direction, each strip-shaped receiving electrode extends along a second direction, the first direction and the second direction are intersected, the strip-shaped driving electrodes and the strip-shaped receiving electrodes are intersected with each other to form a plurality of intersection regions, and the piezoelectric material layer is at least overlapped with the intersection regions.

For example, forming the first electrode layer at one side of the substrate may form the first electrode layer including a plurality of strip-shaped receiving electrodes directly at one side of the substrate through a patterning process. The material of the first electrode layer may be a metal material.

For example, forming the second electrode layer on the side of the piezoelectric material layer away from the first electrode layer includes: forming a plurality of first sub-driving electrodes through a patterning process, wherein each first sub-driving electrode is a strip-shaped sub-electrode extending along a first direction; forming a retaining wall between the adjacent first sub-driving electrodes; and forming a plurality of second sub-drive electrodes which are arranged in one-to-one correspondence with the plurality of first strip-shaped drive electrodes on one sides of the plurality of first sub-drive electrodes, wherein the height of the retaining wall in the direction perpendicular to the second electrode layer is larger than that of the first sub-drive electrodes in the direction perpendicular to the second electrode layer, and the plurality of first sub-drive electrodes and the plurality of second sub-drive electrodes form the plurality of drive electrodes, so that the second electrode layer with larger thickness can be formed, and further, ultrasonic waves with higher strength are generated.

The thickness of the second electrode layer is, for example, greater than 10 microns, and is thus suitable for carrying higher voltages. Through the manufacturing method, a plurality of first sub-driving electrodes can be formed on one side of the piezoelectric material layer away from the first electrode layer, the first sub-driving electrodes do not need to be made thicker, and the thickness range of the first sub-driving electrodes is 0.4-1 micrometer, for example; and then, a plurality of second sub-driving electrodes are formed on the plurality of first sub-driving electrodes by utilizing the retaining walls and an electroplating process in an electroplating mode, so that the driving electrodes with thicker thickness are obtained. It should be noted that, in the electroplating process, under the action of the electric field, the metal layer can continue to grow only on the patterned metal layer, and the retaining wall can play a role in separation, so as to prevent the electroplated metal layers from being connected with each other.

For example, in some examples, the material of the second electrode includes one or more of copper, silver, and aluminum.

For example, retaining walls may be made of resin materials, which may have lower cost and lower manufacturing difficulty.

(1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are referred to, and other structures may refer to general designs.

(2) Features of the disclosure in the same embodiment and in different embodiments may be combined with each other without conflict.

The above is only a specific embodiment of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure, and shall be covered by the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A fingerprint identification structure comprising:

the first electrode layer comprises a plurality of strip-shaped receiving electrodes which are arranged at intervals;

a piezoelectric material layer disposed on one side of the first electrode layer; and

a second electrode layer arranged on one side of the piezoelectric material layer far away from the first electrode layer and including multiple strip-shaped driving electrodes arranged at intervals,

each strip-shaped driving electrode extends along a first direction, each strip-shaped receiving electrode extends along a second direction, the first direction and the second direction are intersected, the strip-shaped driving electrodes and the strip-shaped receiving electrodes are intersected with each other to form a plurality of intersection regions, the piezoelectric material layer is at least overlapped with the intersection regions, and one strip-shaped receiving electrode and the strip-shaped driving electrodes form a plurality of intersection regions.

2. The fingerprint identification structure of claim 1, wherein said piezoelectric material layer comprises spaced apart sub-piezoelectric material layers,

wherein each of the sub piezoelectric material layers extends in the first direction or the second direction.

3. The fingerprint identification structure of claim 1, wherein said layer of piezoelectric material comprises a plurality of sub-blocks of piezoelectric material,

wherein the plurality of blocks of sub-piezoelectric material are arranged in one-to-one correspondence with the plurality of intersection regions.

4. The fingerprint identification structure of any one of claims 1-3, wherein said second electrode layer further comprises: and the retaining wall is positioned between two adjacent strip-shaped driving electrodes.

5. The fingerprint recognition structure according to claim 4, wherein the size of the dam in a direction perpendicular to the piezoelectric material layer is in a range of 1-20 micrometers, and the size of the second electrode layer in a direction perpendicular to the piezoelectric material layer is in a range of 1-20 micrometers.

6. The fingerprint identification structure of any one of claims 1-3, wherein a material of said second electrode layer comprises one or more of copper, silver, and aluminum.

7. The fingerprint identification structure of any one of claims 1-3, further comprising: a plurality of receiving circuits electrically connected to the plurality of strip-shaped receiving electrodes, respectively,

the fingerprint identification structure comprises an effective identification area and an edge area located on the periphery of the effective identification area, the plurality of intersection areas are located in the effective identification area, and the plurality of receiving circuits are located in the edge area.

8. The fingerprint identification structure of claim 7, wherein each of said receiving circuits comprises:

a storage capacitor including a first pole and a second pole;

a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and

a signal reading unit for reading the signal from the optical disk,

the strip-shaped receiving electrode, the first source electrode and the first electrode are connected to a storage node, the signal reading unit is configured to read an electrical signal stored in the storage capacitor, and the first thin film transistor is an oxide thin film transistor.

9. The fingerprint recognition structure according to claim 8, wherein said signal reading unit comprises:

a second thin film transistor including a second gate electrode, a second source electrode, and a second drain electrode; and

a third thin film transistor including a third gate electrode, a third source electrode, and a third drain electrode,

wherein the second gate is connected to the storage node, the second drain is connected to the third source, the second source is configured to apply a fixed voltage, the third gate is configured to apply a readout instruction signal, and the third drain is configured to output a signal.

10. A display device, comprising:

a display panel; and

the fingerprint identification structure of any one of claims 1-6.

11. The display device according to claim 10, wherein the display panel includes a display area and a peripheral area located at a periphery of the display area, and the fingerprint identification structure further includes: a plurality of receiving circuits, the plurality of receiving circuits are respectively electrically connected with the plurality of strip-shaped receiving electrodes, wherein each receiving circuit comprises: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and a signal reading unit, the strip-shaped receiving electrode, the first source electrode and the first pole being connected to a storage node, the signal reading unit being configured to read an electrical signal stored in the storage capacitor,

the plurality of intersection areas are located in the display area, and orthographic projections of the plurality of receiving circuits on the display panel are located in the peripheral area.

12. A display device according to claim 10 or 11, wherein the display panel comprises a light emitting side and the fingerprint identification structure is located on the light emitting side of the display panel.

13. A display device according to claim 10 or 11, wherein the display panel comprises a black matrix or a pixel defining layer, and the orthographic projection of the strip-shaped drive electrodes and the strip-shaped receive electrodes on the display panel at least partially overlaps the black matrix or the pixel defining layer.

14. A driving method of a fingerprint identification structure according to any one of claims 1 to 6, wherein said plurality of strip-shaped driving electrodes are divided into a plurality of strip-shaped driving electrode groups arranged in sequence, each of said strip-shaped driving electrode groups includes N strip-shaped driving electrodes, and two adjacent strip-shaped driving electrode groups share N-1 strip-shaped driving electrodes, said driving method comprising:

sequentially applying driving voltage to the plurality of strip-shaped driving electrode groups to respectively drive the piezoelectric material layers corresponding to the plurality of strip-shaped driving electrode groups to emit ultrasonic waves; and

the piezoelectric material layer is used for receiving ultrasonic waves reflected by fingerprints and outputting corresponding fingerprint electric signals through the strip-shaped receiving electrodes,

wherein N is a positive integer greater than or equal to 1.

15. A driving method for a fingerprint identification structure according to claim 14, wherein N is a positive integer greater than or equal to 2, each of said stripe-shaped driving electrode groups includes a first stripe-shaped driving electrode and a second stripe-shaped driving electrode, and applying a driving voltage to each of said stripe-shaped driving electrode groups includes:

applying a driving voltage to the first strip-shaped driving electrodes at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrodes to emit ultrasonic waves; and

applying a driving voltage to the second strip-shaped driving electrodes at a second time point to delay the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the second strip-shaped driving electrodes from the phase of the ultrasonic wave emitted by the piezoelectric material layer corresponding to the first strip-shaped driving electrodes,

wherein the second time point is delayed from the first time point.

16. The driving method of a fingerprint identification structure of claim 14, wherein N is a positive integer greater than or equal to 3, each of said stripe drive electrode groups comprises a first stripe drive electrode, a second stripe drive electrode and a third stripe drive electrode, and applying a drive voltage to each of said stripe drive electrode groups comprises:

applying a driving voltage to the first strip-shaped driving electrode and the third strip-shaped driving electrode at a first time point so as to drive the piezoelectric material layers corresponding to the first strip-shaped driving electrode and the third strip-shaped driving electrode to emit ultrasonic waves; and

applying a driving voltage to the second strip-shaped driving electrodes at a second time point to delay the phase of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the second strip-shaped driving electrodes from the phase of the ultrasonic waves emitted by the piezoelectric material layers corresponding to the first strip-shaped driving electrodes and the third strip-shaped driving electrodes,

wherein the second time point is delayed from the first time point.

17. The driving method of a fingerprint recognition structure according to any one of claims 14-16, wherein said fingerprint recognition structure further comprises: a plurality of receiving circuits, the plurality of receiving circuits are respectively electrically connected with the plurality of strip-shaped receiving electrodes, wherein each receiving circuit comprises: a storage capacitor including a first pole and a second pole; a first thin film transistor including a first gate electrode, a first source electrode, and a first drain electrode; and a signal reading unit, wherein the strip-shaped receiving electrode, the first source electrode and the first pole are connected to a storage node, the signal reading unit is configured to read an electrical signal stored in the storage capacitor, and receiving an ultrasonic wave reflected by a fingerprint by using the piezoelectric material layer and outputting a corresponding fingerprint electrical signal through the strip-shaped receiving electrode includes:

when a driving voltage is applied to the strip-shaped driving electrode group to drive the piezoelectric material layer corresponding to the strip-shaped driving electrode group to emit ultrasonic waves, a starting signal is applied to the first grid electrode to open the first thin film transistor;

applying bias voltage to the first drain electrode according to the arrival time of the surface echo so as to lift the fingerprint electric signal on the strip-shaped receiving electrode, and storing the lifted fingerprint electric signal in the storage capacitor; and

and reading out the lifted fingerprint electric signal by using the signal reading unit.