Fingerprint recognition structure and driving method thereof, and electronic device

Abstract

A fingerprint recognition structure and a driving method and electronic device thereof. The fingerprint recognition structure comprises: a driving electrode layer, comprising N driving electrodes arranged at intervals; a piezoelectric material layer, located on one side of the driving electrode layer; a receiving electrode layer, located on the side of the piezoelectric material layer away from the driving electrode layer, and comprising M receiving electrodes; an auxiliary driving electrode layer, located on the side of the piezoelectric material layer away from the receiving electrode layer, and arranged in a different layer from the driving electrode layer; and a first insulating layer, located between the driving electrode layer and the auxiliary driving electrode layer, the auxiliary driving electrode layer comprising N auxiliary driving electrodes, the N driving electrodes and the N auxiliary driving electrodes being arranged alternately, and the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer. Thus, the fingerprint recognition structure can improve the ultrasonic emission efficiency of the fingerprint recognition structure.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a fingerprint recognition structure, a driving method of the fingerprint recognition structure, and an electronic device. Background Art

[0002] Fingerprint recognition technology is a technology that compares the detailed feature points of different fingerprints to achieve identity recognition. With the continuous development of smartphones, under-screen fingerprint recognition technology has become one of the research hotspots and development directions in the current smartphone market. At present, under-screen fingerprint recognition technology can be divided into under-screen capacitive fingerprint recognition technology, under-screen ultrasonic fingerprint recognition technology and under-screen optical fingerprint recognition technology. Under-screen ultrasonic fingerprint recognition technology has become the most ideal solution at present due to its strong penetration, high recognition and strong anti-fouling ability.

[0003] The under-screen ultrasonic fingerprint recognition technology realizes fingerprint recognition through an ultrasonic fingerprint recognition structure. Generally, the ultrasonic fingerprint recognition structure is a three-layer structure, including a driving electrode, a receiving electrode, and a piezoelectric layer located between the two. When a driving voltage is applied to the driving electrode and the receiving electrode, the piezoelectric layer is excited by the voltage to produce an inverse piezoelectric effect and emit a first ultrasonic wave outward. After the first ultrasonic wave contacts the finger, it is reflected back by the finger as a second ultrasonic wave. Since the fingerprint includes valleys and ridges, the vibration intensity of the second ultrasonic wave reflected back to the piezoelectric layer by the fingerprint is different. At this time, a fixed voltage is applied to the driving electrode, and the piezoelectric layer can convert the second ultrasonic wave into a voltage signal. The voltage signal is transmitted to the fingerprint recognition module through the receiving electrode, and the position of the valley and ridge in the fingerprint is determined according to the voltage signal. Summary of the invention

[0004] The embodiment of the present disclosure provides a fingerprint recognition structure and a driving method thereof and an electronic device. The fingerprint recognition structure includes: a driving electrode layer, including N driving electrodes arranged at intervals; a piezoelectric material layer, located on one side of the driving electrode layer; a receiving electrode layer, located on the side of the piezoelectric material layer away from the driving electrode layer, and including M receiving electrodes; an auxiliary driving electrode layer, located on the side of the piezoelectric material layer away from the receiving electrode layer, and arranged in a different layer from the driving electrode layer; and a first insulating layer, located between the driving electrode layer and the auxiliary driving electrode layer, the auxiliary driving electrode layer including N auxiliary driving electrodes, the N driving electrodes and the N auxiliary driving electrodes are arranged alternately, the positive projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps the interval between the positive projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, M is a positive integer greater than or equal to 2, N is a positive integer greater than or equal to 2, and i is a positive integer greater than or equal to 1 and less than N. Therefore, the fingerprint recognition structure can drive or excite the piezoelectric material layer located at the interval between adjacent driving electrodes by setting an auxiliary driving electrode layer, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency.

[0005] At least one embodiment of the present disclosure provides a fingerprint recognition structure, which includes: a driving electrode layer, including N driving electrodes arranged at intervals; a piezoelectric material layer, located on one side of the driving electrode layer; a receiving electrode layer, located on a side of the piezoelectric material layer away from the driving electrode layer, and including M receiving electrodes; an auxiliary driving electrode layer, located on a side of the piezoelectric material layer away from the receiving electrode layer, and arranged in a different layer from the driving electrode layer; and a first insulating layer, located between the driving electrode layer and the auxiliary driving electrode layer, the auxiliary driving electrode layer including N auxiliary driving electrodes, the N driving electrodes and the N auxiliary driving electrodes are arranged alternately, the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, M is a positive integer greater than or equal to 2, N is a positive integer greater than or equal to 2, and i is a positive integer greater than or equal to 1 and less than N.

[0006] For example, in the fingerprint recognition structure provided in one embodiment of the present disclosure, the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer completely falls within the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer.

[0007] For example, in a fingerprint recognition structure provided in an embodiment of the present disclosure, the i-th driving electrode and the i-th auxiliary driving electrode are configured to receive the same driving signal, and the N-th driving electrode and the N-th auxiliary driving electrode are configured to receive the same driving signal.

[0008] For example, in a fingerprint recognition structure provided in an embodiment of the present disclosure, the fingerprint recognition structure includes a fingerprint recognition area and a peripheral area surrounding the fingerprint recognition area, the i-th driving electrode and the i-th auxiliary driving electrode are electrically connected in the peripheral area, and the N-th driving electrode and the N-th auxiliary driving electrode are electrically connected in the peripheral area.

[0009] For example, in the fingerprint recognition structure provided in an embodiment of the present disclosure, the orthographic projection of the Nth auxiliary driving electrode on the piezoelectric material layer is located on the side of the orthographic projection of the Nth driving electrode on the piezoelectric material layer away from the N-1th driving electrode.

[0010] For example, in a fingerprint recognition structure provided in an embodiment of the present disclosure, the M receiving electrodes are arranged in an array along a first direction and a second direction, the second direction intersects with the first direction, each of the driving electrodes extends along the first direction, the multiple driving electrodes are arranged along the second direction, and the orthographic projection of each of the N driving electrodes on the piezoelectric material layer at least partially overlaps with the orthographic projection of the multiple receiving electrodes arranged along the first direction on the piezoelectric material layer.

[0011] For example, the fingerprint recognition structure provided by an embodiment of the present disclosure also includes: a conductive auxiliary layer, which is located on a side of the piezoelectric material layer away from the driving electrode layer and is arranged in a different layer from the receiving electrode layer, and the orthographic projection of the conductive auxiliary layer on the piezoelectric material layer overlaps with the interval between the orthographic projections of the M receiving electrodes on the piezoelectric material layer.

[0012] For example, in the fingerprint recognition structure provided in an embodiment of the present disclosure, the conductive auxiliary layer is a conductive grid, and the conductive grid is arranged around the M receiving electrodes.

[0013] For example, in the fingerprint recognition structure provided by an embodiment of the present disclosure, the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the orthographic projection of the conductive grid on the piezoelectric material layer, and the orthographic projection of the N-th auxiliary driving electrode on the piezoelectric material layer overlaps with the orthographic projection of the conductive grid on the piezoelectric material layer.

[0014] For example, in the fingerprint recognition structure provided in an embodiment of the present disclosure, the conductive auxiliary layer is configured to be connected to a fixed potential or to ground.

[0015] For example, the fingerprint recognition structure provided by an embodiment of the present disclosure further includes: a second insulating layer located between the conductive auxiliary layer and the receiving electrode layer.

[0016] For example, in a fingerprint recognition structure provided by an embodiment of the present disclosure, the auxiliary driving electrode layer is located on a side of the driving electrode layer away from the piezoelectric material layer.

[0017] For example, the fingerprint recognition structure provided by an embodiment of the present disclosure further includes: an acoustic wave reflecting layer located on a side of the auxiliary driving electrode layer away from the piezoelectric material layer; and a third insulating layer located between the acoustic wave reflecting layer and the auxiliary driving electrode layer.

[0018] For example, in a fingerprint recognition structure provided in an embodiment of the present disclosure, the material of the piezoelectric material layer includes polyvinylidene fluoride.

[0019] At least one embodiment of the present disclosure further provides an electronic device, comprising any of the above-mentioned fingerprint recognition structures.

[0020] For example, the electronic device provided by one embodiment of the present disclosure also includes: a driving circuit, which is electrically connected to the N driving electrodes and the N auxiliary driving electrodes, respectively, and is configured to apply the same driving signal to the i-th driving electrode and the i-th auxiliary driving electrode, and is configured to apply the same driving signal to the N-th driving electrode and the N-th auxiliary driving electrode.

[0021] At least one embodiment of the present disclosure further provides a driving method for the above-mentioned fingerprint recognition structure, comprising: applying a driving voltage to the i-th driving electrode and the i-th auxiliary driving electrode to drive the piezoelectric material layer corresponding to the i-th driving electrode and the i-th auxiliary driving electrode to emit ultrasonic waves; and using the piezoelectric material layer to receive the ultrasonic waves reflected by the fingerprint and output a corresponding fingerprint electrical signal through at least part of the M receiving electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure.

[0023] Figure 1 A schematic diagram of a fingerprint recognition structure emitting ultrasonic waves;

[0024] Figure 2 A schematic diagram of a fingerprint recognition structure receiving ultrasonic waves;

[0025] Figure 3 A schematic diagram of fingerprint recognition structure for fingerprint recognition;

[0026] Figure 4 It is a structural schematic diagram of a fingerprint recognition structure;

[0027] Figure 5 It is a plan schematic diagram of a fingerprint recognition structure;

[0028] Fig. 6A A plan view of a fingerprint recognition structure provided by an embodiment of the present disclosure;

[0029] Figure 6B A plan view of a fingerprint recognition structure provided by an embodiment of the present disclosure;

[0030] Figure 7 A fingerprint recognition structure provided by an embodiment of the present disclosure is Figure 6B Schematic diagram of the cross section in the AA direction;

[0031] Figure 8 A plan view of another fingerprint recognition structure provided by an embodiment of the present disclosure;

[0032] Fig. 9 A fingerprint recognition structure provided by an embodiment of the present disclosure is Figure 8 Schematic diagram of the cross section in the BB direction;

[0033] Fig.10 A schematic diagram of the structure of an electronic device provided by an embodiment of the present disclosure; and

[0034] Fig.11 A schematic diagram of the structure of another electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0036] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0037] Figure 1 A schematic diagram of a fingerprint recognition structure emitting ultrasonic waves; Figure 2 This is a schematic diagram of a fingerprint recognition structure receiving ultrasonic waves. Figure 1 As shown, 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 piezoelectric material and can be excited by voltage to produce an inverse piezoelectric effect. Figure 1 As shown, 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 will deform due to the inverse piezoelectric effect or drive the membrane layers above and below the piezoelectric layer 13 to vibrate together, thereby generating ultrasonic waves and emitting them outward. It should be noted that when a cavity (for example, an air cavity) is provided on the side of the upper electrode 11 away from the piezoelectric layer 13 or the side of the lower electrode 12 away from the piezoelectric layer 13, the ultrasonic waves emitted by the ultrasonic sensor will be strengthened, so that the ultrasonic waves can be better emitted.

[0038] like Figure 2 As shown, 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 in 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 or sense the alternating voltage generated by the piezoelectric layer. Since the fingerprint 500 includes valleys 510 and ridges 520, they have different reflection capabilities for ultrasonic waves (the valley 510 has a stronger reflection capability for ultrasonic waves), resulting in different intensities of ultrasonic waves reflected by the valleys 510 and the ridges 520. Therefore, the alternating voltage received or sensed by the receiving electrode can be used to determine whether the ultrasonic wave is reflected by the valley or the ridge.

[0039] Figure 3 The following is a schematic diagram of a fingerprint recognition structure for fingerprint recognition. Figure 3As shown, the fingerprint recognition 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 the side of the upper electrode 11 away from the piezoelectric layer 13, and a protective layer 90 located on the 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 ultrasonic waves and receive ultrasonic waves, that is, the ultrasonic sensor 10 serves as both an ultrasonic transmitting sensor and an ultrasonic receiving sensor. When the fingerprint contacts 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 in the piezoelectric layer; at this time, the upper electrode 11 is grounded, and the plurality of lower electrodes 12 can serve as receiving electrodes, so as to realize receiving the alternating voltage generated by the piezoelectric layer at different positions. Since the fingerprint 500 includes valleys 510 and ridges 520, which have different reflection capabilities for ultrasound (the valleys 510 have stronger reflection capabilities for ultrasound), the intensities of ultrasound reflected by the valleys 510 and ridges 520 are different. Therefore, the position information of the valleys and ridges in the fingerprint 500 can be obtained through the alternating voltages received by the multiple lower electrodes 12, thereby realizing fingerprint recognition.

[0040] Figure 4 FIG. 1 is a schematic diagram of a fingerprint recognition structure. Figure 4 As shown, the upper electrode 11, the lower electrode 12 and the piezoelectric layer 13 can all be made on the same side of the thin film transistor substrate 91. The fingerprint recognition structure also includes: a bias resistor 60 and a binding pad 70; the bias resistor 60 can be used to calibrate the voltage, and the binding pad 70 can be used to bind an external circuit.

[0041] Figure 5 Figure 1 is a schematic diagram of a fingerprint recognition structure. Figure 5 As shown, the fingerprint recognition structure includes a plurality of receiving electrodes 11 arranged in an array, a plurality of strip-shaped driving electrodes 12, and a piezoelectric layer 13 located between the plurality of receiving electrodes 11 and the plurality of strip-shaped driving electrodes 12. The fingerprint recognition structure can realize the focusing (phase-increment interference) of ultrasonic waves by driving the plurality of strip-shaped driving electrodes, thereby increasing the intensity or energy of the emitted ultrasonic waves in a specific area, thereby improving the fingerprint recognition performance, and also making the emitted ultrasonic waves have better directionality, thereby reducing the crosstalk between the valleys and ridges of the fingerprint, thereby improving the fingerprint recognition performance.

[0042] However, since the plurality of strip-shaped driving electrodes need to be driven individually, that is, different driving signals are applied, the plurality of strip-shaped driving electrodes need to be spaced apart to be insulated from each other. In this case, there is a space between adjacent strip-shaped driving electrodes, and the piezoelectric layer at the spaced position cannot be effectively excited, so that the ultrasonic emission efficiency cannot be maximized.

[0043] In this regard, the embodiment of the present disclosure provides a fingerprint recognition structure and a driving method thereof and an electronic device. The fingerprint recognition structure includes: a driving electrode layer, including N driving electrodes arranged at intervals; a piezoelectric material layer, located on one side of the driving electrode layer; a receiving electrode layer, located on the side of the piezoelectric material layer away from the driving electrode layer, and including M receiving electrodes; an auxiliary driving electrode layer, located on the side of the piezoelectric material layer away from the receiving electrode layer, and arranged in a different layer from the driving electrode layer; and a first insulating layer, located between the driving electrode layer and the auxiliary driving electrode layer, the auxiliary driving electrode layer including N auxiliary driving electrodes, the N driving electrodes and the N auxiliary driving electrodes are arranged alternately, the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, M is a positive integer greater than or equal to 2, N is a positive integer greater than or equal to 2, and i is a positive integer greater than or equal to 1 and less than N. Therefore, the fingerprint recognition structure can drive or excite the piezoelectric material layer located at the interval between adjacent driving electrodes by setting an auxiliary driving electrode layer, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency.

[0044] The fingerprint recognition structure and its driving method and electronic device provided by the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0045] An embodiment of the present disclosure provides a fingerprint recognition structure. Fig. 6A A plan view of a fingerprint recognition structure provided by an embodiment of the present disclosure; Figure 6B A plan view of a fingerprint recognition structure provided by an embodiment of the present disclosure; Figure 7 A fingerprint recognition structure provided by an embodiment of the present disclosure is Figure 6B Schematic diagram of the cross section along the AA direction.

[0046] like Fig. 6A , Figure 6B and Figure 7As shown, the fingerprint recognition structure 100 includes a driving electrode layer 110, a receiving electrode layer 120, a piezoelectric material layer 130, an auxiliary driving electrode layer 140 and a first insulating layer 151; the piezoelectric material layer 130 is located on one side of the driving electrode layer 110, and the receiving electrode layer 120 is located on the side of the piezoelectric material layer 130 away from the driving electrode layer 110, that is, the piezoelectric material layer 130 is located between the driving electrode layer 110 and the receiving electrode layer 120; the auxiliary driving electrode layer 140 is located on the side of the piezoelectric material layer 130 away from the receiving electrode layer 120, and is arranged in a different layer from the driving electrode layer 110; the first insulating layer 151 is located between the driving electrode layer 110 and the auxiliary driving electrode layer 140. The driving electrode layer 110 includes N driving electrodes 114 arranged at intervals; the receiving electrode layer 120 includes M receiving electrodes 124; the auxiliary driving electrode layer 140 includes N auxiliary driving electrodes 144; the N driving electrodes 114 and the N auxiliary driving electrodes 144 are arranged alternately, and the orthographic projection of the i-th auxiliary driving electrode 144 on the piezoelectric material layer 130 overlaps with the interval between the orthographic projections of the i-th driving electrode 114 and the i+1-th driving electrode 114 on the piezoelectric material layer 130, M is a positive integer greater than or equal to 2, N is a positive integer greater than or equal to 2, and i is a positive integer greater than or equal to 1 and less than N.

[0047] In the fingerprint recognition structure provided by the embodiment of the present disclosure, since the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, the fingerprint recognition structure can drive or excite the piezoelectric material layer located in the interval between adjacent driving electrodes by setting an auxiliary driving electrode layer, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency.

[0048] For example, the material of the driving electrode includes one or more of copper, silver and aluminum; the material of the receiving electrode may also include one or more of copper, silver and aluminum. Of course, the materials of the driving electrode and the receiving electrode may also be other suitable conductive materials, which are not limited in the embodiments of the present disclosure.

[0049] In some examples, such as Fig. 6A , Figure 6B and Figure 7As shown, the interval between the orthographic projections of the i-th driving electrode 114 and the i+1-th driving electrode 114 on the piezoelectric material layer 130 completely falls within the orthographic projection of the i-th auxiliary driving electrode 144 on the piezoelectric material layer 130. In other words, the interval between the orthographic projections of two adjacent driving electrodes 114 on the piezoelectric material layer 130 completely falls within the orthographic projections of the corresponding auxiliary driving electrodes 144 on the piezoelectric material layer 130. Thus, the fingerprint recognition structure can maximize the use of the auxiliary driving electrodes to drive or excite the piezoelectric material layer located at the interval between adjacent driving electrodes.

[0050] In some examples, such as Fig. 6A , Figure 6B and Figure 7 As shown, the i-th driving electrode 114 and the i-th auxiliary driving electrode 144 are configured to receive the same driving signal, and the N-th driving electrode 114 and the N-th auxiliary driving electrode 144 are configured to receive the same driving signal. That is, the i-th driving electrode 114 and the i-th auxiliary driving electrode 144 can apply a driving voltage to the piezoelectric material layer 130 as a whole, and the N-th driving electrode 114 and the N-th auxiliary driving electrode 144 can apply a driving voltage to the piezoelectric material layer 130 as a whole.

[0051] For example, after applying a driving voltage to the ith driving electrode and the ith auxiliary driving electrode, the piezoelectric material layer corresponding to the ith driving electrode and the ith auxiliary driving electrode will deform due to the inverse piezoelectric effect or drive the film layer above and below the piezoelectric material layer to vibrate together, thereby generating ultrasonic waves and emitting them outward. Therefore, compared with the case where the driving electrode is used alone, the fingerprint recognition structure can drive or excite a larger area of ​​the piezoelectric material layer through the ith driving electrode and the ith auxiliary driving electrode, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency. On the other hand, the fingerprint recognition structure can also realize ultrasonic focusing (phase-increment interference) by driving the above-mentioned multiple driving electrodes separately, thereby increasing the intensity or energy of the emitted ultrasonic wave in a specific area, thereby improving the fingerprint recognition performance, and also making the emitted ultrasonic wave have better directionality, thereby reducing the crosstalk between the valleys and ridges of the fingerprint, thereby improving the fingerprint recognition performance. When the fingerprint recognition structure increases the intensity or energy of the emitted ultrasonic wave in a specific area or specific direction by focusing the ultrasonic wave (additive interference), the fingerprint recognition structure can not only realize fingerprint recognition, but also penetrate the finger to distinguish whether the fingerprint is real skin.

[0052] In some examples, such as Fig. 6A and Figure 6BAs shown, the fingerprint recognition structure 100 includes a fingerprint recognition area 101 and a peripheral area 102 surrounding the fingerprint recognition area 101, the i-th driving electrode 114 and the i-th auxiliary driving electrode 144 are electrically connected in the peripheral area 102, and the N-th driving electrode 114 and the N-th auxiliary driving electrode 144 are electrically connected in the peripheral area 102. Therefore, the i-th driving electrode 114 and the i-th auxiliary driving electrode 144 can be applied with the same driving signal by the driving circuit, and the N-th driving electrode 114 and the N-th auxiliary driving electrode 144 can be applied with the same driving signal by the driving circuit.

[0053] In some examples, such as Fig. 6A , Figure 6B and Figure 7 As shown, the orthographic projection of the Nth auxiliary driving electrode 144 on the piezoelectric material layer 130 is located on a side of the orthographic projection of the Nth driving electrode 114 on the piezoelectric material layer 130 away from the N−1th driving electrode 114 .

[0054] In some examples, such as Fig. 6A , Figure 6B and Figure 7 As shown, M receiving electrodes 124 are arranged in an array along a first direction and a second direction, the second direction intersects with the first direction, each driving electrode 114 extends along the first direction, and multiple driving electrodes 114 are arranged along the second direction, and the orthographic projection of each of the N driving electrodes 114 on the piezoelectric material layer 130 at least partially overlaps with the orthographic projection of the multiple receiving electrodes 124 arranged along the first direction on the piezoelectric material layer 130.

[0055] For example, each of the driving electrodes 114 mentioned above may be a strip-shaped driving electrode extending along the first direction, and the width of the strip-shaped driving electrode may be in the range of 50-70 micrometers.

[0056] and Fig. 6A The fingerprint recognition structure shown is different in that Figure 6B and Figure 7 The fingerprint recognition structure shown also includes a conductive auxiliary layer 160. The conductive auxiliary layer 160 is located on the side of the piezoelectric material layer 130 away from the driving electrode layer 110, and is arranged in a different layer from the receiving electrode layer 120. The orthographic projection of the conductive auxiliary layer 160 on the piezoelectric material layer 130 overlaps with the interval between the orthographic projections of the M receiving electrodes 124 on the piezoelectric material layer 130. In other words, the conductive auxiliary layer 160 is arranged at a position between the M receiving electrodes 124. Thus, the conductive auxiliary layer 160 can be arranged opposite to the auxiliary driving layer 140, so that each auxiliary driving electrode can better generate an electric field with the conductive auxiliary layer, thereby driving the piezoelectric material layer.

[0057] In some examples, such as Figure 6B and Figure 7As shown, the conductive auxiliary layer 160 is a conductive grid, and the conductive grid is arranged around the M receiving electrodes 124. Therefore, the conductive grid can be applied with a fixed potential or grounded as a whole, so as to generate an electric field with the auxiliary driving electrodes.

[0058] In some examples, such as Figure 6B and Figure 7 As shown, the orthographic projection of the i-th auxiliary driving electrode 114 on the piezoelectric material layer 130 overlaps with the orthographic projection of the conductive grid 160 on the piezoelectric material layer 130. The orthographic projection of the N-th auxiliary driving electrode 114 on the piezoelectric material layer 130 overlaps with the orthographic projection of the conductive grid 160 on the piezoelectric material layer 130. Thus, the conductive auxiliary layer 160 can be arranged opposite to the auxiliary driving layer 140, so that each auxiliary driving electrode can better generate an electric field with the conductive auxiliary layer, thereby driving the piezoelectric material layer.

[0059] In some examples, the conductive auxiliary layer 160 is configured to be connected to a fixed potential or ground.

[0060] In some examples, such as Figure 7 As shown, the fingerprint recognition structure 100 further includes: a second insulating layer 152 located between the conductive auxiliary layer 160 and the receiving electrode layer 124 .

[0061] In some examples, such as Figure 7 As shown, the auxiliary driving electrode layer 140 is located on the side of the driving electrode layer 120 away from the piezoelectric material layer 130. Since the area of ​​each driving electrode 114 in the driving electrode layer 120 is larger than the area of ​​each auxiliary driving electrode 144 in the auxiliary driving electrode layer 140, the driving electrode layer 120 is arranged closer to the piezoelectric material layer 130, or even in contact with the piezoelectric material layer 130, so as to improve the ultrasonic emission efficiency.

[0062] In some examples, such as Figure 7 As shown, the conductive auxiliary layer 160 is located on the side of the receiving electrode layer 120 close to the piezoelectric material layer 130. At this time, the above-mentioned second insulating layer 152 is arranged between the receiving electrode layer 120 and the piezoelectric material layer 130. The second insulating layer 152 can prevent the piezoelectric material layer 130 from being broken down by the driving voltage, and a large charge or voltage from the piezoelectric material layer enters the receiving electrode and destroys the receiving circuit connected to the receiving electrode. As a result, the fingerprint recognition structure has high security and stability. It should be noted that the receiving electrode can read the information about the reflected ultrasonic wave on the piezoelectric material layer by sensing the charge or voltage on the piezoelectric material layer.

[0063] In some examples, such as Figure 7As shown, the fingerprint recognition structure 100 further includes: an acoustic wave reflecting layer 170 located on a side of the auxiliary driving electrode layer 140 away from the piezoelectric material layer 130 ; and a third insulating layer 153 located between the acoustic wave reflecting layer 170 and the auxiliary driving electrode layer 140 .

[0064] In some examples, the material of the piezoelectric material layer includes polyvinylidene fluoride. Of course, the embodiments of the present disclosure include but are not limited to this, and the material of the piezoelectric material layer can also be made of piezoelectric materials such as ALN (aluminum nitride) and PZT (lead zirconate titanate piezoelectric ceramics).

[0065] In some examples, such as Figure 7 As shown, the fingerprint recognition structure 100 further includes: a receiving circuit layer 190, which is located on a side of the receiving electrode layer 120 away from the piezoelectric material layer 130. The receiving circuit layer 190 may include M receiving circuit units (not shown); the M receiving circuit units are arranged in a one-to-one correspondence with the above-mentioned M receiving electrodes, so as to receive signals from the M receiving electrodes.

[0066] In some examples, such as Figure 7 As shown, the fingerprint recognition structure 100 further includes a protection layer 195 located on a side of the sound wave reflection layer 170 away from the auxiliary driving electrode layer 140 . The protection layer 195 can protect the fingerprint recognition structure 100 .

[0067] For example, the material of the protective layer may be an organic insulating material, such as epoxy resin. Of course, the embodiments of the present disclosure include but are not limited to the above.

[0068] An embodiment of the present disclosure also provides a fingerprint recognition module. Figure 8 A plan view of another fingerprint recognition structure provided by an embodiment of the present disclosure; Fig. 9 A fingerprint recognition structure provided by an embodiment of the present disclosure is Figure 8 Schematic diagram of the cross section along the BB direction.

[0069] like Figure 8 and Fig. 9As shown, each receiving electrode 124 extends along the second direction, M receiving electrodes 124 are arranged along the first direction, each driving electrode 114 extends along the first direction, and multiple driving electrodes 114 are arranged along the second direction. At this time, the M receiving electrodes 124 and the N driving electrodes 114 are arranged to cross each other, thereby forming a plurality of crossing regions 180, and the piezoelectric material layer 130 located in each crossing region 180 can be driven or excited by the corresponding driving electrode 114 and receiving electrode 124. At this time, the fingerprint recognition structure 100 also includes the auxiliary driving electrode layer 140 mentioned above, which is located on the side of the piezoelectric material layer 130 away from the receiving electrode layer 120 and is arranged in a different layer from the driving electrode layer 110; the auxiliary driving electrode layer 140 includes N auxiliary driving electrodes 144; the N driving electrodes 114 and the N auxiliary driving electrodes 144 are arranged alternately, and the positive projection of the i-th auxiliary driving electrode 144 on the piezoelectric material layer 130 overlaps with the interval between the positive projections of the i-th driving electrode 114 and the i+1-th driving electrode 114 on the piezoelectric material layer 130. Similarly, since the positive projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the interval between the positive projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, the fingerprint recognition structure can drive or excite the piezoelectric material layer located in the interval between adjacent driving electrodes by setting the auxiliary driving electrode layer, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency.

[0070] At least one embodiment of the present disclosure also provides an electronic device. Fig.10 FIG. 1 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present disclosure. Fig.10 As shown, the electronic device 200 includes the above-mentioned fingerprint recognition structure 100. Since the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, the fingerprint recognition structure can drive or excite the piezoelectric material layer located in the interval between adjacent driving electrodes by setting an auxiliary driving electrode layer, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency. Therefore, the electronic device can have a higher fingerprint recognition performance. In some examples, such as Fig.10 As shown, the electronic device 200 further includes a display module 210, which is located on a side of the receiving electrode layer 120 away from the driving electrode layer 110. At this time, the electronic device 200 can not only realize the fingerprint recognition function, but also realize the display function.

[0071] For example, the display module 210 may be a liquid crystal display module (LCD) or an organic light emitting diode display module (OLED). Of course, the embodiments of the present disclosure include but are not limited to the above.

[0072] In some examples, such as Fig.10 As shown, the electronic device 200 further includes a cover plate 220, which is located on a side of the display module 210 away from the fingerprint recognition structure 100. The surface of the cover plate 220 away from the fingerprint recognition structure 100 can be used as a touch operation surface.

[0073] Fig.11 FIG. 1 is a schematic diagram of the structure of another electronic device provided by an embodiment of the present disclosure. Fig.11 As shown, the electronic device 200 further includes a driving circuit 250, which is electrically connected to the N driving electrodes 114 and the N auxiliary driving electrodes 144, respectively, and is configured to apply the same driving signal to the i-th driving electrode 114 and the i-th auxiliary driving electrode 144, and is configured to apply the same driving signal to the N-th driving electrode 114 and the N-th auxiliary driving electrode 144. For example, the electronic device may be an electronic device with a display function, such as a television, a mobile phone, a computer, a laptop computer, an electronic photo album, a navigator, etc.

[0074] At least one embodiment of the present disclosure further provides a driving method of a fingerprint recognition structure, which includes the following steps S101-S102.

[0075] Step S101: applying a driving voltage to the i-th driving electrode and the i-th auxiliary driving electrode to drive the piezoelectric material layers corresponding to the i-th driving electrode and the i-th auxiliary driving electrode to emit ultrasonic waves.

[0076] Step S102: using the piezoelectric material layer to receive the ultrasonic wave reflected by the fingerprint and outputting the corresponding fingerprint electrical signal through at least part of the M receiving electrodes.

[0077] In the driving method of the fingerprint recognition structure, after applying the driving voltage to the i-th driving electrode and the i-th auxiliary driving electrode, the piezoelectric material layer corresponding to the i-th driving electrode and the i-th auxiliary driving electrode will deform due to the inverse piezoelectric effect or drive the film layer above and below the piezoelectric material layer to vibrate together, thereby generating ultrasonic waves and emitting them outward. Therefore, compared with the case of driving only by the driving electrode, the driving method can drive or excite a larger area of ​​the piezoelectric material layer through the i-th driving electrode and the i-th auxiliary driving electrode, thereby improving the ultrasonic emission efficiency of the fingerprint recognition structure and maximizing the ultrasonic emission efficiency. Therefore, the electronic device can have a higher fingerprint recognition performance.

[0078] (1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can refer to the general design.

[0079] (2) In the absence of conflict, features in the same embodiment or in different embodiments of the present disclosure may be combined with each other.

[0080] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A fingerprint recognition structure, comprising: A driving electrode layer, comprising N driving electrodes arranged at intervals; A piezoelectric material layer, located on one side of the driving electrode layer; A receiving electrode layer, located at a side of the piezoelectric material layer away from the driving electrode layer, and comprising M receiving electrodes; an auxiliary driving electrode layer, located at a side of the piezoelectric material layer away from the receiving electrode layer, and arranged in a different layer from the driving electrode layer; as well as a first insulating layer, located between the driving electrode layer and the auxiliary driving electrode layer; Wherein, the auxiliary driving electrode layer includes N auxiliary driving electrodes, the N driving electrodes and the N auxiliary driving electrodes are arranged alternately, the orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the interval between the orthographic projections of the i-th driving electrode and the i+1-th driving electrode on the piezoelectric material layer, M is a positive integer greater than or equal to 2, N is a positive integer greater than or equal to 2, and i is a positive integer greater than or equal to 1 and less than N.

2. The fingerprint recognition structure according to claim 1, wherein: The interval between the orthographic projections of the ith driving electrode and the (i+1)th driving electrode on the piezoelectric material layer completely falls within the orthographic projection of the ith auxiliary driving electrode on the piezoelectric material layer.

3. The fingerprint recognition structure according to claim 1, wherein: The i-th driving electrode and the i-th auxiliary driving electrode are configured to receive the same driving signal, and the N-th driving electrode and the N-th auxiliary driving electrode are configured to receive the same driving signal.

4. The fingerprint recognition structure according to claim 1, wherein: The fingerprint recognition structure includes a fingerprint recognition area and a peripheral area surrounding the fingerprint recognition area. The i-th driving electrode and the i-th auxiliary driving electrode are electrically connected in the peripheral area, and the N-th driving electrode and the N-th auxiliary driving electrode are electrically connected in the peripheral area.

5. The fingerprint recognition structure according to claim 1, wherein: The orthographic projection of the Nth auxiliary driving electrode on the piezoelectric material layer is located on a side of the orthographic projection of the Nth driving electrode on the piezoelectric material layer away from the N-1th driving electrode.

6. The fingerprint recognition structure according to any one of claims 1 to 5, wherein: The M receiving electrodes are arranged in an array along a first direction and a second direction, the second direction intersects the first direction, each of the driving electrodes extends along the first direction, and the plurality of driving electrodes are arranged along the second direction. The orthographic projection of each of the N driving electrodes on the piezoelectric material layer at least partially overlaps with the orthographic projection of the plurality of receiving electrodes arranged along the first direction on the piezoelectric material layer.

7. The fingerprint recognition structure according to claim 6, further comprising: The conductive auxiliary layer is located on a side of the piezoelectric material layer away from the driving electrode layer and is arranged in a different layer from the receiving electrode layer. The orthographic projection of the conductive auxiliary layer on the piezoelectric material layer overlaps with the interval between the orthographic projections of the M receiving electrodes on the piezoelectric material layer.

8. The fingerprint recognition structure according to claim 7, wherein: The conductive auxiliary layer is a conductive grid, and the conductive grid is arranged around the M receiving electrodes.

9. The fingerprint recognition structure according to claim 8, wherein: The orthographic projection of the i-th auxiliary driving electrode on the piezoelectric material layer overlaps with the orthographic projection of the conductive grid on the piezoelectric material layer, and the orthographic projection of the N-th auxiliary driving electrode on the piezoelectric material layer overlaps with the orthographic projection of the conductive grid on the piezoelectric material layer.

10. The fingerprint recognition structure according to claim 7, wherein: The conductive auxiliary layer is configured to be connected to a fixed potential or to ground.

11. The fingerprint recognition structure according to claim 7, further comprising: The second insulating layer is located between the conductive auxiliary layer and the receiving electrode layer.

12. The fingerprint recognition structure according to any one of claims 1 to 5, wherein: The auxiliary driving electrode layer is located at a side of the driving electrode layer away from the piezoelectric material layer.

13. The fingerprint recognition structure according to any one of claims 1 to 5, further comprising: an acoustic wave reflecting layer, located on a side of the auxiliary driving electrode layer away from the piezoelectric material layer; as well as The third insulating layer is located between the sound wave reflecting layer and the auxiliary driving electrode layer.

14. The fingerprint recognition structure according to any one of claims 1 to 5, wherein: The material of the piezoelectric material layer includes polyvinylidene fluoride.

15. An electronic device comprising the fingerprint recognition structure according to any one of claims 1-14.

16. The electronic device according to claim 15, further comprising: The driving circuit is electrically connected to the N driving electrodes and the N auxiliary driving electrodes respectively, and is configured to apply the same driving signal to the i-th driving electrode and the i-th auxiliary driving electrode, and is configured to apply the same driving signal to the N-th driving electrode and the N-th auxiliary driving electrode.

17. A method for driving a fingerprint recognition structure according to any one of claims 1 to 14, comprising: Applying a driving voltage to the i-th driving electrode and the i-th auxiliary driving electrode to drive the piezoelectric material layers corresponding to the i-th driving electrode and the i-th auxiliary driving electrode to emit ultrasonic waves; as well as The piezoelectric material layer is used to receive the ultrasonic wave reflected by the fingerprint and output the corresponding fingerprint electrical signal through at least part of the M receiving electrodes.

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