Ultrasonic fingerprint recognition device and electronic device

Abstract

The present application provides an ultrasonic fingerprint recognition device and an electronic device. The ultrasonic fingerprint recognition device is arranged under the cover of the electronic device to realize ultrasonic fingerprint recognition, including an ultrasonic fingerprint recognition chip, a matching layer stacked on the ultrasonic fingerprint recognition chip, and a second electrode arranged relative to the matching layer. The ultrasonic fingerprint recognition chip includes a substrate, a first electrode, a pixel electrode array, and a piezoelectric layer. The first electrode receives a driving signal to drive the piezoelectric layer to excite an ultrasonic signal, and the second electrode receives a second driving signal to detect the self-capacitance between the second electrode and the finger to realize fingerprint recognition of the finger. Separating the shared touch sensing signal driving signal can avoid the existence of high voltage in the second electrode to reduce the voltage resistance design requirements of the chip circuit, and also improve the sensitivity of self-capacitance detection. Furthermore, it also adds more flexible and diverse application forms, which is convenient for flexible adjustment of the stacking in different application scenarios.

Description

Technical Field

[0001] The present application relates to the field of fingerprint recognition technology, and in particular to an ultrasonic fingerprint recognition device and an electronic device. Background Art

[0002] Ultrasonic fingerprint recognition technology is currently widely used in electronic devices under the organic light-emitting diode (OLED) display screen. Ultrasonic fingerprint recognition technology can also be used under non-OLED display screens, such as under the cover plate. Figure 1 The ultrasonic fingerprint recognition device shown.

[0003] like Figure 1 As shown, the ultrasonic fingerprint recognition chip 100 is attached to the bottom of the cover plate 300 through the matching layer 200, wherein the ultrasonic fingerprint recognition chip 100 includes a first electrode 101 and a pixel electrode array 102, and a piezoelectric layer 103 sandwiched between the two. When the ultrasonic fingerprint recognition device works in the ultrasonic mode, the driving signal drives the first electrode 101 to generate and receive ultrasonic waves; when working in finger touch detection, the capacitance C between the first electrode 101 and the finger is detected through the touch sensing signal. 1 When the finger is pressed to the ultrasonic fingerprint area, the capacitance C 1 The touch sensitivity of the finger can be determined by the sensor.

[0004] However, if Figure 1 The driving signal and the touch sensing signal share the first electrode 101, but there are the following problems:

[0005] First, the driving signal usually drives a voltage of tens or even hundreds of volts, which is too high for the touch sensing circuit connected to the touch sensing signal, thus being detrimental to the design of the chip circuit;

[0006] Second, the first electrode 101 and the pixel electrode array 102 sandwich the piezoelectric layer 103, which can be equivalent to a flat plate capacitor C 0 , its capacitance value is very large, usually reaching 150pF, and the capacitance C generated by finger pressing 1 Only 1pF, because C 0 Much larger than C 1 , which will cause the change of touch sensing signal to C 1 Insensitive, that is, C 0 The existence of C 1 The detection sensitivity becomes very low, thereby reducing the detection sensitivity of the ultrasonic fingerprint recognition device;

[0007] Furthermore, the design of the shared first electrode 101 requires that the first electrode 101 faces the finger to achieve finger touch detection, which is not conducive to the ultrasonic fingerprint recognition device to flexibly adjust the stacking in practical applications and brings limitations to the structure of the ultrasonic fingerprint recognition device. Summary of the invention

[0008] The present application provides an ultrasonic fingerprint recognition device and an electronic device, which are used to solve the technical problems in the prior art that the touch sensing signal and the driving signal of the ultrasonic fingerprint recognition device share the same first electrode, which is not conducive to chip circuit design, reduces detection sensitivity, and has application limitations.

[0009] In a first aspect, the present application provides an ultrasonic fingerprint recognition device, which is arranged under a cover plate of an electronic device to realize ultrasonic fingerprint recognition, comprising: an ultrasonic fingerprint recognition chip, a matching layer stacked on the ultrasonic fingerprint recognition chip, and a second electrode arranged relative to the matching layer;

[0010] The ultrasonic fingerprint recognition chip includes a substrate, a first electrode, a pixel electrode array and a piezoelectric layer;

[0011] The first electrode receives a driving signal to drive the piezoelectric layer to excite an ultrasonic signal, and the second electrode outputs a touch sensing signal to detect the self-capacitance between the second electrode and a finger to perform fingerprint recognition of the finger.

[0012] In a possible design, the matching layer includes a first adhesive layer, an interlayer, and a second adhesive layer stacked in sequence from top to bottom, and the interlayer is formed of a conductive material with high acoustic impedance.

[0013] In a possible design, the second electrode is located in the interlayer.

[0014] In a possible design, the second electrode is disposed around the matching layer.

[0015] In a possible design, the material forming the first adhesive layer and the second adhesive layer is acrylic acid or epoxy resin.

[0016] In a possible design, the conductive material with high acoustic impedance includes metal.

[0017] In a possible design, the piezoelectric layer has a thickness of 7 μm to 11 μm.

[0018] In a possible design, the ultrasonic fingerprint recognition chip includes:

[0019] The substrate, the pixel electrode array, the piezoelectric layer and the first electrode are stacked in sequence from bottom to top; or

[0020] The first electrode, the piezoelectric layer, the pixel electrode array and the substrate are stacked in sequence from bottom to top.

[0021] In a possible design, an electrode layer is arranged above or below the piezoelectric layer, and the first electrode is arranged on the electrode layer.

[0022] In a possible design, the electrode layer is formed of silver paste, and the thickness of the silver paste is 4 μm to 30 μm.

[0023] In a possible design, a circuit board is also included, which is pressed and electrically connected to the ultrasonic fingerprint recognition chip.

[0024] In a possible design, if the first electrode layer is stacked on the piezoelectric layer, it also includes a reinforcing sheet adhered to the circuit board to fix the circuit board, and the ultrasonic fingerprint recognition chip is arranged on the surface of the reinforcing sheet.

[0025] In a second aspect, the present application provides an electronic device, comprising: a cover plate, and any possible ultrasonic fingerprint recognition device provided in the first aspect;

[0026] The cover plate is used to provide a finger pressing area and receive the pressing of the finger;

[0027] The ultrasonic fingerprint recognition device is arranged below the cover plate and is used to detect the fingerprint of the finger pressed on the cover plate.

[0028] In a possible design, the cover plate is formed of a conductive material or a non-conductive material.

[0029] In a possible design, if the cover plate is formed of the conductive material, an insulating coating is provided on the surface of the cover plate, and the thickness of the cover plate is 0.1 mm to 1.5 mm.

[0030] In a possible design, if the cover plate is formed of the non-conductive material, the thickness of the cover plate is less than or equal to 3 mm.

[0031] In a possible design, the conductive material is metal, and the non-conductive material is plastic or glass.

[0032] The present application provides an ultrasonic fingerprint recognition device and an electronic device. The ultrasonic fingerprint recognition device is arranged under the cover of the electronic device to realize ultrasonic fingerprint recognition, and includes an ultrasonic fingerprint recognition chip, a matching layer stacked on the ultrasonic fingerprint recognition chip, and a second electrode arranged relative to the matching layer. The ultrasonic fingerprint recognition chip includes a substrate, a first electrode, a pixel electrode array, and a piezoelectric layer. The first electrode receives a driving signal to drive the piezoelectric layer to excite an ultrasonic signal, and the second electrode receives a second driving signal to detect the self-capacitance between the second electrode and the finger to realize fingerprint recognition of the finger. The second electrode that outputs the touch sensing signal for fingerprint recognition is separated from the first electrode that receives the driving signal. On the one hand, it can avoid the existence of high voltage in the second electrode to reduce the voltage resistance design requirements of the chip circuit. On the other hand, it improves the sensitivity of finger self-capacitance detection. Moreover, it can also increase more flexible and diverse application forms, which is convenient for flexible adjustment of the stacking in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 It is a schematic diagram of an ultrasonic fingerprint recognition device in the prior art;

[0035] Figure 2 A schematic diagram of the structure of an ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0036] Figure 3 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0038] Figure 5 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0039] Figure 6 A top view of an ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0040] Figure 7 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0041] Figure 8A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0042] Fig. 9 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0043] Fig.10 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application;

[0044] Fig.11 A schematic diagram of the structure of another ultrasonic fingerprint recognition device provided in an embodiment of the present application.

[0045] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0046] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of methods and devices consistent with some aspects of the present application as detailed in the appended claims.

[0047] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0048] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or apparatus.

[0049] like Figure 1There are several problems with the driving signal and the touch sensing signal of the ultrasonic fingerprint recognition device in the prior art: first, the driving signal usually drives a voltage of tens or even hundreds of volts, which is too high for the touch sensing circuit connected to the touch sensing signal, thus being unfavorable for the design of the chip circuit; second, the first electrode 101 and the pixel electrode array 102 sandwich the piezoelectric layer 103, which can be equivalent to a flat plate capacitor C 0 , its capacitance value is very large, usually reaching 150pF, and the capacitance C generated by finger pressing 1 Only 1pF, because C 0 Much larger than C 1 , which will cause the change of touch sensing signal to C 1 Insensitive, that is, C 0 The existence of C 1 The detection sensitivity becomes very low, thereby reducing the detection sensitivity of the ultrasonic fingerprint recognition device; furthermore, the design of the shared first electrode 101 must require that the first electrode 101 faces the finger to achieve finger touch detection, which is not conducive to the ultrasonic fingerprint recognition device to flexibly adjust the stacking in actual applications, and brings limitations to the structure of the ultrasonic fingerprint recognition device.

[0050] In view of the above problems in the prior art, the present application provides an ultrasonic fingerprint recognition device and an electronic device. The inventive concept of the ultrasonic fingerprint recognition device provided by the present application is to separate the electrodes for receiving the driving signal and outputting the touch sensing signal, that is, to add a second electrode, and use the original first electrode to receive the driving signal to generate and receive the ultrasonic signal. The second electrode is connected to the touch sensing signal detection circuit, and the touch sensing signal is detected to detect the capacitance change between the second electrode and the finger to realize the judgment of the finger touch sensing. The second electrode is designed to be separated from the first electrode. On the one hand, since the second electrode does not need to withstand the high voltage of the driving signal, it can avoid reducing the voltage resistance design requirements of the chip circuit due to the high voltage in the second electrode. On the other hand, it improves the sensitivity of the finger self-capacitance detection. Moreover, it can also increase more flexible and diverse application forms, which is convenient for flexible adjustment of the stacking in different application scenarios.

[0051] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0052] Figure 2 This is a schematic diagram of the structure of an ultrasonic fingerprint recognition device provided in an embodiment of the present application. Figure 2As shown, the ultrasonic fingerprint recognition device is arranged under the cover plate 10 of the electronic device to realize ultrasonic fingerprint recognition.

[0053] The ultrasonic fingerprint recognition device includes: an ultrasonic fingerprint recognition chip 201 , a matching layer 202 stacked on the ultrasonic fingerprint recognition chip 201 , and a second electrode 203 arranged relative to the matching layer 202 .

[0054] The ultrasonic fingerprint recognition chip 201 includes a substrate 2011 , a first electrode 2012 , a pixel electrode array 2013 and a piezoelectric layer 2014 .

[0055] Optionally, the substrate 2011 may be a silicon substrate formed by a silicon-complementary metal-oxide-semiconductor (CMOS) process.

[0056] The ultrasonic fingerprint recognition device works in ultrasonic mode. The first electrode 2012 receives the driving signal to drive the piezoelectric layer 2014 to excite the ultrasonic signal. The ultrasonic signal is reflected by the finger 21 to form an ultrasonic signal carrying fingerprint information, that is, an ultrasonic fingerprint feedback signal, which is used to identify the fingerprint information of the finger. During touch detection, the touch sensing signal is the self-capacitance between the second electrode 203 and the finger 21 (the capacitance of the electrode itself to the reference ground GND, referred to as self-capacitance.) C 1 The change of is characterized, and the second electrode 203 outputs a touch sensing signal for detecting the self-capacitance C formed between the second electrode 203 and the finger 21. 1 , thereby realizing touch detection of finger 21.

[0057] It can be seen that the first electrode 2012 is used to receive a driving signal for generating an ultrasonic signal, and receives an ultrasonic fingerprint feedback signal carrying a fingerprint signal returned by the finger, and the second electrode 204 is used to receive a touch sensing signal for touch detection, and separates the common electrode of the driving signal and the touch sensing signal in the prior art. The first electrode 2012 and the second electrode 203 each perform their respective functions, and the second electrode 203 does not need to withstand the high voltage of the driving signal, thereby avoiding the disadvantages of high voltage on the chip circuit design. In addition, a planar parasitic capacitor will be formed between the second electrode 203 and the first electrode 2012, and the parasitic capacitor can be reduced by controlling the thickness and dielectric constant of the material between the two electrodes, thereby reducing the size of the parasitic capacitance of the second electrode 203 to the ground (GND), avoiding excessive parasitic capacitance and reducing the self-capacitance C 1 detection sensitivity.

[0058] In addition, due to the separate design of the first electrode 2012 and the second electrode 203, the first electrode 2012 is no longer required to face the finger 21, thereby expanding the flexible adjustment of the stacking in different application scenarios.

[0059] For example Figure 2 As shown in the figure, the pixel electrode array 2013 is arranged above the substrate 2011, the piezoelectric layer 2014 is stacked on the pixel electrode array 2013, and the first electrode 2012 is stacked on the piezoelectric layer 2014, that is, the substrate 2011, the pixel electrode array 2013, the piezoelectric layer 204 and the first electrode 2012 are stacked in sequence from bottom to top to form an ultrasonic fingerprint recognition chip 201 with a positive structure.

[0060] In some embodiments, such as Figure 3 As shown, the ultrasonic fingerprint recognition chip 201 can also be a flip-chip structure, that is, the first electrode 2012 is the bottom layer, the piezoelectric layer 2014 is stacked on the first electrode 2012, the pixel electrode array 2013 is stacked on the piezoelectric layer 2014, and the substrate 2011 is stacked on the pixel electrode array 2013, that is, the first electrode 2012, the piezoelectric layer 2014, the pixel electrode array 2013 and the substrate 2011 are stacked in sequence from bottom to top.

[0061] Furthermore, in the ultrasonic fingerprint recognition chip 201 with a flip-chip structure, the first electrode 2012 is completely unable to sense the capacitance C 1 , but the second electrode 203 can still sense the capacitance C normally 1 Moreover, at this time, the parasitic capacitance of the second electrode 203 to GND can be greatly reduced, which is beneficial to improve the capacitance C 1 Sensitivity of detection.

[0062] Continue to refer to Figure 2 and Figure 3 As shown, the second electrode 203 may be disposed in the matching layer 202 .

[0063] For example, the matching layer 202 is composed of a sandwich between two adhesive layers. Specifically, the matching layer 202 includes a first adhesive layer 2021 , a sandwich layer, and a second adhesive layer 2023 stacked in sequence from top to bottom.

[0064] The matching layer 202 is used to achieve acoustic impedance matching between the ultrasonic fingerprint recognition chip 201 and the cover plate 10 , so as to increase the energy of ultrasonic waves penetrating into the cover plate 10 .

[0065] By adjusting the thickness of the adhesive layer and the interlayer, the acoustic matching effect of the matching layer 202 can be adjusted. Figure 4 and Figure 5 As shown in the mezzanine 2022.

[0066] In some embodiments, the first adhesive layer 2021 and the second adhesive layer 2023 may be made of acrylic or epoxy resin, etc., with a thickness of 3-10 μm. The interlayer may be made of a conductive material with high acoustic impedance, such as copper, aluminum, gold, silver, stainless steel, etc., with a thickness of 5-40 μm.

[0067] In some embodiments, the matching layer 202 may also be formed by mixing high impedance powder and epoxy resin. The acoustic impedance of the matching layer 202 may be adjusted by adjusting the proportion of the high impedance powder.

[0068] In one possible design, Figure 2 and Figure 3 As shown, the second electrode 203 may be disposed in the interlayer, so that the second electrode 203 serves as a component of the matching layer 202 .

[0069] Optionally, in some embodiments, the second electrode 203 may be separated from the matching layer 202, such as Figure 4 and Figure 5 As shown, the second electrode 203 is disposed around the matching layer 202. For example, the second electrode 203 can be a ring electrode disposed around the matching layer 202.

[0070] It should be noted that Figure 4 The second electrode 203 of the ultrasonic fingerprint recognition chip 201 in the upright structure is arranged around the matching layer 202. Figure 5 It is a diagram showing that the second electrode 203 of the ultrasonic fingerprint recognition chip 201 with a flip-chip structure is disposed around the matching layer 202 .

[0071] Reference Figure 6 As shown, Figure 6 It is a top view when the second electrode 203 is arranged around the matching layer 202. The second electrode 203 is removed from the matching layer 202 and arranged around the matching layer 202, which can also be regarded as the surrounding of the ultrasonic fingerprint recognition chip 201, which can further reduce the parasitic capacitance of the second electrode 203 to GND and avoid the influence of the second electrode 203 on the matching layer 202.

[0072] In a possible design, the piezoelectric layer 2014 of the ultrasonic fingerprint recognition device provided in the embodiment of the present application may be a piezoelectric film material having a piezoelectric effect, and its thickness may be 7 μm to 11 μm.

[0073] In a possible design, the first electrode 2012 of the ultrasonic fingerprint recognition device provided in the embodiment of the present application may be disposed in an electrode layer. For example, an electrode layer is disposed above or below the piezoelectric layer 2014, and the first electrode 2012 is disposed in the electrode layer.

[0074] Specifically, an electrode layer such as the face-up structure of the ultrasonic fingerprint recognition chip 201 is arranged on the piezoelectric layer 2014 , and an electrode layer such as the face-down structure of the ultrasonic fingerprint recognition device is arranged under the piezoelectric layer 2014 .

[0075] Optionally, the electrode layer may be formed of silver paste, and the thickness of the silver paste may be 4 μm to 30 μm. Generally speaking, the thicker the silver paste, the lower the corresponding operating frequency; the thinner the thickness, the higher the operating frequency.

[0076] The ultrasonic fingerprint recognition device provided in the above embodiment may further include: a circuit board 205, such as Figures 7 to 10 shown.

[0077] The circuit board 205 is pressed and electrically connected to the ultrasonic fingerprint recognition chip 201. For example, the ultrasonic fingerprint recognition chip can be connected to the ultrasonic fingerprint recognition chip through a gold wire (such as Figures 7 to 10 As shown) the binding process is connected to the circuit board 205 line to achieve electrical connection between the two.

[0078] Optionally, the circuit board 205 may be, for example, a flexible printed circuit (FPC), which is a printed circuit board made of polyimide or polyester film as a substrate and has high reliability and excellent flexibility.

[0079] On the basis of the above embodiment, optionally, if the first electrode 2012 is stacked on the piezoelectric layer 2014 , that is, the ultrasonic fingerprint recognition chip 201 is in a front-mounted structure, the ultrasonic fingerprint recognition device further includes a reinforcing sheet 206 .

[0080] like Figure 7 and Fig. 9 As shown, the ultrasonic fingerprint recognition chip 201 is disposed on the surface of the reinforcing sheet 206 , and the reinforcing sheet 206 is attached to the circuit board 205 to fix the circuit board 205 .

[0081] It should be noted that if Figure 8 and Fig.10 When the ultrasonic fingerprint recognition chip 201 shown is a flip-chip structure, the ultrasonic fingerprint recognition chip 201 is directly attached to the matching layer 202, and the reinforcing sheet 205 is omitted. The reinforcing sheet 205 may not be provided.

[0082] It can be seen from the description of the above embodiments that the ultrasonic fingerprint recognition device provided in the embodiments of the present application can be arranged under the cover of an electronic device to realize ultrasonic fingerprint recognition, and the ultrasonic fingerprint recognition device includes an ultrasonic fingerprint recognition chip, a matching layer stacked on the ultrasonic fingerprint recognition chip, and a second electrode arranged relative to the matching layer. The ultrasonic fingerprint recognition chip includes a substrate, a first electrode, a pixel electrode array, and a piezoelectric layer. The first electrode receives a driving signal to drive the piezoelectric layer to excite an ultrasonic signal, and the second electrode receives a second driving signal to detect the self-capacitance between the second electrode and the finger to realize fingerprint recognition of the finger.

[0083] The second electrode that outputs the touch sensing signal for fingerprint recognition is designed to be separated from the first electrode that receives the driving signal. On the one hand, it can avoid the existence of high voltage in the second electrode to reduce the voltage resistance design requirements of the chip circuit. On the other hand, it improves the sensitivity of finger self-capacitance detection. Furthermore, it can also increase more flexible and diverse application forms, making it convenient to flexibly adjust the stacking in different application scenarios.

[0084] Based on the above embodiments, an embodiment of the present application further provides an electronic device, which may include a cover plate 10 and an ultrasonic fingerprint recognition device as provided in the above embodiments.

[0085] The cover plate 10 is used to provide a pressing area for the finger 21 and receive the pressing of the finger 21;

[0086] The ultrasonic fingerprint recognition device is disposed under the cover plate 10 and is used to detect the fingerprint of the finger 21 pressed on the cover plate 10 .

[0087] Furthermore, the cover plate 10 provided in the above embodiments may be formed of a conductive material or a non-conductive material.

[0088] In some embodiments, if the cover plate 10 is formed of a conductive material, such as Fig.11 As shown, in order to prevent the conductive cover from short-circuiting to the ground (GND), an insulating coating 11 is usually added to the surface of the cover 10. The finger 21 can press on the insulating coating 11, which can also change the capacitance C between the second electrode 203 and the finger 21. 1 The change of can also realize the fingerprint detection of finger pressing. Fig.11 The capacitor C 1 ' and C 1 "The parallel connection forms a capacitor C 1 .

[0089] It should be noted that Fig.11 Only in Figure 7The above is an illustration based on the above, but not limited to it. That is, if the cover plate 10 shown in the above embodiments is formed of a conductive material, an insulating layer 11 is required to be provided on its surface to prevent the cover plate 10 from being short-circuited to the ground.

[0090] In a possible design, if the cover plate 10 is formed of a conductive material, such as metal, the thickness of the cover plate 10 can be set to between 0.1 mm and 1.5 mm.

[0091] In some embodiments, if the cover is formed of a non-conductive material, such as plastic or glass, the thickness of the cover 10 may be less than or equal to 3 mm.

[0092] In some embodiments, the ultrasonic fingerprint recognition device can be set on any surface of the electronic device that interacts with the user, including but not limited to the front of the electronic device.

[0093] In some embodiments, the type of electronic device may be, for example, a smart door lock, a smart switch, a smart wearable device, or other non-OLED screen device that can realize the finger touch detection function. The embodiments of the present application do not limit the type of electronic device.

[0094] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0095] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. An ultrasonic fingerprint recognition device, characterized in that: It is arranged under the cover of the electronic device to realize ultrasonic fingerprint recognition, and includes: an ultrasonic fingerprint recognition chip, a matching layer stacked on the ultrasonic fingerprint recognition chip, and a second electrode arranged relative to the matching layer; The matching layer comprises a first adhesive layer, an interlayer and a second adhesive layer stacked in sequence from top to bottom, and the acoustic matching effect of the matching layer is adjusted by adjusting the thickness of the adhesive layer and the interlayer, the first adhesive layer and the second adhesive layer are formed of acrylic acid or epoxy resin, the interlayer is formed of a conductive material with high acoustic impedance, the second electrode is located in the interlayer, or the second electrode is arranged around the matching layer; The ultrasonic fingerprint recognition chip includes a substrate, a first electrode, a pixel electrode array and a piezoelectric layer; The first electrode receives a driving signal to drive the piezoelectric layer to excite an ultrasonic signal, and the second electrode outputs a touch sensing signal to detect the self-capacitance between the second electrode and a finger to perform fingerprint recognition of the finger.

2. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: The conductive material with high acoustic impedance includes metal.

3. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: The thickness of the piezoelectric layer is 7 μm to 11 μm.

4. The ultrasonic fingerprint recognition device according to any one of claims 1 to 3, characterized in that: The ultrasonic fingerprint recognition chip comprises: The substrate, the pixel electrode array, the piezoelectric layer and the first electrode are stacked in sequence from bottom to top; or The first electrode, the piezoelectric layer, the pixel electrode array and the substrate are stacked in sequence from bottom to top.

5. The ultrasonic fingerprint recognition device according to claim 4, characterized in that: An electrode layer is arranged on or below the piezoelectric layer, and the first electrode is arranged on the electrode layer.

6. The ultrasonic fingerprint recognition device according to claim 5, characterized in that: The electrode layer is formed of silver paste, and the thickness of the silver paste is 4 μm-30 μm.

7. The ultrasonic fingerprint recognition device according to claim 6, characterized in that: It also includes a circuit board, which is pressed and electrically connected to the ultrasonic fingerprint recognition chip.

8. The ultrasonic fingerprint recognition device according to claim 7, characterized in that: If the first electrode is stacked on the piezoelectric layer, a reinforcing sheet is further included, which is attached to the circuit board to fix the circuit board, and the ultrasonic fingerprint recognition chip is arranged on the surface of the reinforcing sheet.

9. An electronic device, characterized in that: include: A cover plate, and an ultrasonic fingerprint recognition device according to any one of claims 1 to 8; The cover plate is used to provide a finger pressing area and receive the pressing of the finger; The ultrasonic fingerprint recognition device is arranged below the cover plate and is used to detect the fingerprint of the finger pressed on the cover plate.

10. The electronic device according to claim 9, characterized in that: The cover plate is formed of a conductive material or a non-conductive material.

11. The electronic device according to claim 10, characterized in that: If the cover plate is formed of the conductive material, an insulating coating is provided on the surface of the cover plate, and the thickness of the cover plate is 0.1 mm to 1.5 mm.

12. The electronic device according to claim 10, characterized in that: If the cover plate is formed of the non-conductive material, the thickness of the cover plate is less than or equal to 3 mm.

13. The electronic device according to claim 10, characterized in that: The conductive material is metal, and the non-conductive material is plastic or glass.

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