Fingerprint recognition components and electronic devices

Abstract

The embodiment of the present invention provides a fingerprint recognition component and an electronic device, wherein the fingerprint recognition component includes a fingerprint sensor and a protective layer, wherein the protective layer is arranged at the bottom of the fingerprint sensor opposite to the top, wherein the surface of the top is a fingerprint recognition sensing surface; the fingerprint sensor is used to emit and recognize ultrasonic waves, and the protective layer shields electromagnetic interference. By setting the protective layer, electromagnetic interference shielding can be achieved; in addition, the protective layer can be made very thin, and no air layer is required, which can significantly reduce the overall thickness of the fingerprint recognition component, so that the thickness of the electronic device can be made thinner.

Description

Technical Field

[0001] The present invention belongs to the technical field of fingerprint recognition, and in particular relates to a fingerprint recognition component and an electronic device. Background Art

[0002] Ultrasonic fingerprint recognition is an emerging fingerprint recognition technology. Together with optical fingerprint recognition, it has become one of the two main under-screen fingerprint recognition solutions. The ultrasonic fingerprint recognition module emits ultrasonic waves, which pass through the display and glass cover to detect the user's fingerprint. The ultrasonic waves are reflected back to the ultrasonic fingerprint recognition module to be received and recognized.

[0003] The accuracy of current ultrasonic fingerprint recognition is affected by the internal environment of the electronic device. After the ultrasonic wave is emitted, it will be emitted into the electronic device. The ultrasonic wave reflected back by the device inside the electronic device will interfere with the ultrasonic fingerprint recognition module. Therefore, it is necessary to protect the ultrasonic fingerprint recognition module against electromagnetic interference. The current technical means is to wrap a protective cover around the module. However, the protective cover needs to be spaced from the module to form a space with an air layer so that the ultrasonic wave can decay rapidly in the air layer. The scheme of setting a protective cover in the prior art makes the overall thickness of the fingerprint recognition module and the protective cover very thick, generally reaching 645μm, which is not conducive to the thinness of electronic devices. Summary of the invention

[0004] The purpose of the present invention is to provide a fingerprint recognition component and an electronic device. A protective layer is set on the fingerprint recognition component, which can shield electromagnetic interference and does not need to set an air layer, thereby reducing the thickness.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a fingerprint recognition component, including a fingerprint sensor and a protective layer, wherein the protective layer is arranged at the bottom of the fingerprint sensor opposite to the top, wherein the surface of the top is a fingerprint recognition sensing surface; the fingerprint sensor is used to emit and recognize ultrasonic waves, and the protective layer is used to shield electromagnetic interference.

[0007] By setting a protective layer, electromagnetic interference can be shielded, so that the fingerprint sensor is less likely to be interfered with by electrical signals from other devices inside the electronic device. In addition, the protective layer can be made very thin. Compared with the shielding cover in the prior art that reduces ultrasonic and electrical signal interference, there is no need to set an air layer, which can significantly reduce the overall thickness of the fingerprint recognition component, making the thickness of the electronic device thinner.

[0008] Wherein, the protective layer is conductive ink, and the components of the conductive ink include thermoplastic resin and carbon powder. The thermoplastic resin and the carbon powder are combined to make the acoustic impedance of the conductive ink match the fingerprint sensor, so that ultrasound can pass through the conductive ink.

[0009] The conductive ink also includes solvents, additives and defoamers. The thermoplastic resin is used to form a paint film. The carbon powder is used for conductivity and electromagnetic shielding. The additive can increase the functions of the conductive ink in certain aspects. The defoamer can reduce bubbles in the conductive ink, improve the leveling of the conductive ink, and prevent defects such as shrinkage holes or pinholes.

[0010] The proportion of the thermoplastic resin is 30%-45%, the proportion of the carbon powder is 40%-55%, the proportion of the solvent is 10%-15%, the proportion of the auxiliary agent is 2%-4%, and the proportion of the defoaming agent is 0.5%-1%. The appropriate proportions of the above components are set so that the conductive ink meets the performance requirements of electromagnetic shielding.

[0011] Wherein, the thermoplastic resin is 2,2'-[(1-methylethylene)bis(4,1-phenylenecarboxaldehyde)]dioxirane polymer; the solvent is a divalent acid ester; the auxiliary agent is a leveling agent; and the defoaming agent is silicone oil.

[0012] The fingerprint sensor includes a stacked TFT substrate, a piezoelectric layer and an electrode layer, the protective layer is arranged on the surface of the TFT substrate facing away from the piezoelectric layer, the TFT substrate and the electrode layer are used to generate a voltage on the piezoelectric layer, so that the piezoelectric layer emits an ultrasonic wave, and the piezoelectric layer receives the ultrasonic wave and generates an electrical signal and transmits it to the TFT substrate. By arranging the TFT substrate, the piezoelectric layer and the electrode layer, the TFT substrate and the electrode layer apply a voltage to the electrode layer, so that the fingerprint recognition component can emit and receive ultrasonic waves.

[0013] The fingerprint recognition component further includes a circuit board and a driver chip, wherein the circuit board is connected to the TFT substrate and the electrode layer, and the driver chip is connected to the circuit board. By providing the circuit board and the driver chip, the fingerprint sensor can emit ultrasonic waves under the action of the driver chip, and can process the ultrasonic electrical signal of the fingerprint sensor to identify the fingerprint.

[0014] The end of the electrode layer extends to the surface of the TFT substrate, the circuit board is connected to the TFT substrate and the end of the electrode layer, and the circuit board is located on the side of the TFT substrate facing the piezoelectric layer, and the driver chip is arranged on the surface of the circuit board facing away from the TFT substrate. By setting the connection relationship and setting position of the circuit board and the driver chip, the overall structure of the fingerprint recognition component is compact and easy to install.

[0015] Among them, the fingerprint sensor also includes a DAF layer and a bonding layer stacked on the electrode layer; the bonding layer is used to bond with the cover assembly; the DAF layer is used to raise the height of the fingerprint sensor to avoid interference between the driver chip and the cover assembly.

[0016] In the second aspect, an embodiment of the present invention further provides an electronic device, characterized in that it includes a cover assembly and a fingerprint recognition component described in any one of the various embodiments of the first aspect, the fingerprint recognition component is arranged on the inner surface of the cover assembly relative to the outer surface, the outer surface of the cover assembly is used to contact with a finger, the fingerprint recognition component emits ultrasonic waves and passes through the cover assembly, and is reflected at the fingerprint of the finger and received by the fingerprint recognition component. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a schematic cross-sectional structural diagram of a fingerprint recognition component of an embodiment;

[0019] Figure 2 It is the pattern of the fake finger fingerprint recognized by the fingerprint recognition component;

[0020] Figure 3 It is the pattern of the real finger fingerprint recognized by the fingerprint recognition component. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please refer to Figure 1 An embodiment of the present invention provides an electronic device, such as a tablet computer, a personal digital assistant (PDA), a smart phone, etc. The electronic device includes a fingerprint recognition component and a cover component 50. The fingerprint recognition component includes a fingerprint module and a protective layer 20. The fingerprint module includes a fingerprint sensor 10, a circuit board 30 and a driver chip 40.

[0023] In this embodiment, the cover plate assembly 50 includes a cover bottom ink 51, a cover plate 52 and a protective film 53 which are stacked. Among them, the cover plate 52 can be a rigid material such as glass, or a flexible material such as PET or PC, that is, the cover plate 52 can be rigid or flexible. When the fingerprint recognition component is arranged on the display surface side of the electronic device, the cover bottom ink 51 surrounds the edges of the cover plate 52 to block the terminal area of ​​the display screen. When the fingerprint recognition component is arranged on the side of the electronic device facing away from the display surface (i.e., the back cover), the cover bottom ink 51 can cover the entire cover plate 52. The protective film 53 can be an ordinary plastic film, a tempered film, or an anti-fingerprint film (AF Coating). In other embodiments, the cover plate assembly 50 can also include a display screen, which is arranged on the side of the cover bottom ink 51 facing away from the cover plate 52. The display screen is preferably an OLED screen that can transmit ultrasound. Further, the cover plate assembly 50 can also include a touch layer, which can be arranged between the display screen and the cover bottom ink 51.

[0024] The fingerprint recognition component is arranged on the inner surface of the cover plate component 50 opposite to the outer surface, the inner surface is the surface of the cover bottom ink 51 facing away from the cover plate 52, and the outer surface is used to contact the fingerprint of the user's finger. The fingerprint recognition component emits ultrasonic waves and passes through the cover plate component 50. The ultrasonic waves are reflected at the fingerprint of the user's finger and received by the fingerprint recognition component to obtain fingerprint information through the reflected ultrasonic waves.

[0025] The electronic device can realize ultrasonic fingerprint recognition on the outer surface of the cover assembly 50 by arranging the fingerprint recognition component on the inner surface of the cover assembly 50. Compared with the existing hole-digging pressing or wiping capacitive fingerprint recognition, it does not need to change the structure of the cover assembly 50, has a simple structure, is easy to implement, and has low cost.

[0026] In one embodiment, the fingerprint recognition component is arranged in the visible area of ​​the cover assembly 50 relative to the non-visible area, the non-visible area is arranged at the periphery of the visible area, and the visible area is the display area of ​​the display screen. That is, the fingerprint recognition component is arranged below the display screen, thereby realizing the fingerprint recognition function under the screen. This embodiment can make the visible area as large as possible, and can reduce the area of ​​the non-visible area as much as possible, thereby realizing a narrow frame.

[0027] In another embodiment, the fingerprint recognition component is arranged at the edge of the cover assembly 50 and is located in the non-display area. The display screen and the fingerprint recognition component are staggered and do not overlap. The ultrasonic waves emitted by the fingerprint recognition component of this embodiment do not need to pass through the display screen, which can improve the recognition speed and accuracy. The disadvantage is that the area of ​​the non-display area on one side is slightly larger, which can be applied to electronic devices with a "chin".

[0028] The fingerprint sensor 10 includes a stacked TFT substrate 11, an electrode connection layer 12, a piezoelectric layer 13, and an electrode layer 14. The protective layer 20 is disposed on the surface of the TFT substrate 11 that is opposite to the electrode connection layer 12. The electrode connection layer 12 is used to connect the TFT substrate 11 and the piezoelectric layer 13. The TFT substrate 11 and the electrode layer 14 are used to generate a voltage on the piezoelectric layer 13, so that the piezoelectric layer 13 emits an ultrasonic wave. The piezoelectric layer 13 receives the ultrasonic wave and generates an electrical signal and transmits it to the TFT substrate 11.

[0029] Among them, the TFT substrate 11 includes a substrate and a plurality of thin film transistors arranged in an array manner on the substrate and a circuit on the substrate for connecting each thin film transistor. In addition, the TFT substrate 11 can amplify the electrical signal and perform other processing. In one embodiment, the TFT substrate 11 uses a thin film as a substrate, and the cover assembly 50 is also a flexible material, so as to meet the flexibility requirements of the entire electronic device. In another embodiment, the TFT substrate 11 uses glass as a substrate. The function of the TFT substrate is to transmit electrical signals to the piezoelectric layer 13, and it can receive electrical signals. The received electrical signals can be electrical signals at any position including the piezoelectric layer 13.

[0030] The piezoelectric layer 13 is made of a piezoelectric material, such as a ferroelectric polymer P (VDF-TrFE). The piezoelectric layer 13 can convert electrical signals and mechanical signals into each other, that is, it can transmit and receive ultrasonic waves.

[0031] The electrode layer 14 is made of a conductive material, such as silver paste. The electrode layer 14 can form a voltage with the TFT substrate 11 and apply it to the surface of the piezoelectric layer 13, so that the piezoelectric layer 13 starts to transmit or receive ultrasonic waves.

[0032] By providing the TFT substrate 11, the piezoelectric layer 13 and the electrode layer 14, the TFT substrate 11 and the electrode layer 14 apply voltage to the electrode layer 14, so that the fingerprint recognition component can transmit and receive ultrasonic waves.

[0033] The fingerprint recognition component further includes a circuit board 30 and a driving chip 40. The circuit board 30 is connected to the TFT substrate 11 and the electrode layer 14 via the connecting terminal 31, and the driving chip 40 is connected to the circuit board 30. By providing the circuit board 30 and the driving chip 40, the fingerprint sensor 10 can emit ultrasonic waves under the action of the driving chip 40, and can process the electrical signal of the ultrasonic waves of the fingerprint sensor 10 to identify the fingerprint.

[0034] The circuit board 30 is preferably a flexible circuit board (FPC), which is thin and space-saving. Optionally, the circuit board 30 may also be a printed circuit board (PCB).

[0035] The driver chip 40 is, for example, an ASIC (Application Specific Integrated Circuit) chip. The driver chip 40 provides a control signal to the fingerprint sensor 10 (for example, sends a high-frequency electrical signal to the fingerprint sensor 10) so that the fingerprint sensor 10 emits ultrasonic waves. Specifically, the driver chip 40 sends a control signal to the TFT substrate 11 and the electrode layer 14 through the circuit board 30, so that the TFT substrate 11 and the electrode layer 14 generate a voltage and apply it to the piezoelectric layer 13, so that the piezoelectric layer 13 emits ultrasonic waves. In addition, the driver chip 40 also receives the electrical signal obtained by the fingerprint sensor 10 converting the reflected ultrasonic wave to identify the fingerprint. Specifically, the piezoelectric layer 13 receives the reflected ultrasonic wave and generates an electrical signal, which is transmitted to the TFT substrate 11 and then transmitted to the driver chip 40 via the circuit board 30.

[0036] The end of the electrode layer 14 extends to the surface of the TFT substrate 11, and the circuit board 30 is connected to the TFT substrate 11 and the end of the electrode layer 14 through the connection terminal 31. The circuit board 30 is located on the side of the TFT substrate 11 facing the piezoelectric layer 13, and the driving chip 40 is arranged on the surface of the circuit board 30 facing away from the TFT substrate 11. By setting the connection relationship and setting position of the circuit board 30 and the driving chip 40, the overall structure of the fingerprint recognition component is compact and easy to install.

[0037] The fingerprint sensor 10 further includes a DAF (Die Attach Film) layer 15 and an adhesive layer 16 stacked on the electrode layer 14. The adhesive layer 16 is used to be bonded to the cover assembly 50, and can be bonded to the cover bottom ink 51 or the cover 52 to fix the fingerprint sensor 10. The DAF layer 15 is used to raise the height of the fingerprint sensor 10 to avoid interference between the driver chip 50 and the cover assembly 50.

[0038] Among them, if the DAF layer 15 is not provided, when the electrode layer 14 is directly connected to the cover assembly 50 through the adhesive layer 16, the overall height of the fingerprint sensor 10 is insufficient, which may cause the driver chip 40 on the circuit board 30 to interfere with the cover assembly 50 and cannot be installed. Therefore, the DAF layer 15 can raise the height of the fingerprint sensor 10 to ensure that there is no interference and facilitate installation. In addition, the DAF layer 15 can also protect the electrode layer 14 and prevent the electrode layer 14 from being oxidized. In addition, the DAF layer can also adjust the frequency of the electrical signal of the electrode layer 14.

[0039] The adhesive layer 16 may be an optical adhesive, and is used to bond the cover assembly 50 and the fingerprint sensor 10. The Young's modulus of the adhesive layer 16 should be as large as possible to avoid weakening the ultrasonic wave.

[0040] Furthermore, the fingerprint recognition component further includes a protective layer 20. The protective layer 20 is disposed on the bottom of the fingerprint sensor 10 opposite to the top, wherein the surface of the top is an ultrasonic wave transmitting surface and a fingerprint recognition sensing surface. The protective layer 20 is used to shield electromagnetic interference.

[0041] By providing the protection layer 20 , electromagnetic interference can be shielded, so that the fingerprint sensor 10 is less interfered by electrical signals of other devices inside the electronic device.

[0042] In addition, the protective layer 20 can be made very thin, for example, the thickness can be 5μm-20μm, preferably 10μm, so that the overall thickness of the fingerprint sensor 10 and the protective layer 20 can be 325μm. Compared with the shielding cover solution for reducing ultrasonic and electrical signal interference in the prior art, there is no need to set up an air layer, which can significantly reduce the overall thickness of the fingerprint recognition component, so that the thickness of the electronic device can be made thinner.

[0043] The protective layer 20 is conductive ink, and the conductive ink includes thermoplastic resin and carbon powder, and the thermoplastic resin and carbon powder are combined to match the acoustic impedance of the conductive ink with the fingerprint sensor 10, so that ultrasonic waves can pass through the conductive ink.

[0044] In order to achieve the above functions, the conductive ink is composed of thermoplastic resin, carbon powder, solvent, additive and defoamer. The thermoplastic resin is a functional resin to form a paint film. Carbon powder plays the role of conductivity and electromagnetic shielding. At the same time, due to its black material, it can be used for light shielding. The solvent is used as a solvent for the conductive ink, and the additive can increase the functions of the conductive ink in certain aspects. The defoamer can reduce the bubbles in the conductive ink, improve the leveling of the conductive ink, and prevent defects such as shrinkage holes or pinholes.

[0045] The proportion of thermoplastic resin is 30%-45%, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, preferably 35%-40%. The proportion of carbon powder is 40%-55%, for example, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, preferably 45%-50%. The proportion of solvent is 10%-15%, for example, 10%, 11%, 12%, 13%, 14%, 15%, preferably 12%-15%. The proportion of the auxiliary agent is 2% to 4%, for example, 2%, 3%, 4%. The proportion of the defoamer is 0.5% to 1%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%. The appropriate proportions of the above components are set so that the conductive ink meets the performance requirements of electromagnetic shielding.

[0046] Preferably, the thermoplastic resin is 2,2'-[(1-methylethylene)bis(4,1-phenylenecarboxaldehyde)]dioxirane polymer; the solvent is a divalent acid ester; the auxiliary agent is a leveling agent; and the defoaming agent is silicone oil. Among them, the auxiliary agent can be 1-hydroxycyclohexylphenyl ketone, which can increase the leveling property of the ink and make the ink surface flat and smooth.

[0047] When applying, please refer to Figure 2 and Figure 3 ,in Figure 2 The fake finger fingerprint pattern recognized by the fingerprint recognition component, Figure 3 The fingerprint pattern of the real finger recognized by the fingerprint recognition component. Taking the case where the cover component 50 is a glass cover, the fingerprint recognition component of the present invention is used to test the fingerprints of the real finger and the fake finger. Figure 2 and Figure 3 , you can see that the fingerprint outline is clearly visible, and the fingerprint unlocking function can be realized. At the same time, in order to avoid the interference of fake fingerprints, the fingerprint recognition algorithm can be optimized to achieve the FRR (False Rejection Rate, commonly understood as the probability of "treating fingerprints that should be matched successfully as unmatched fingerprints") of real fingerprints = 0.97%, FAR (False Acceptance Rate, commonly understood as the probability of "treating fingerprints that should not be matched as matched fingerprints"). ) = 0.0002%.

[0048] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of implementing the above-mentioned embodiment and making equivalent changes according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A fingerprint recognition component, characterized in that: It comprises a fingerprint sensor and a protective layer, wherein the protective layer is closely attached to the bottom of the fingerprint sensor opposite to the top, wherein the surface of the top is a fingerprint recognition sensing surface; the fingerprint sensor is used to emit and recognize ultrasonic waves, and the protective layer is used to shield electromagnetic interference; The protective layer is conductive ink, and the conductive ink includes thermoplastic resin and carbon powder. The thermoplastic resin and the carbon powder are matched to make the acoustic impedance of the conductive ink match the fingerprint sensor, so that the ultrasonic wave can pass through the conductive ink; The conductive ink also includes solvents, additives and defoamers; The proportion of the thermoplastic resin is 30%-45%; the proportion of the carbon powder is 40%-55%; the proportion of the solvent is 10%-15%; the proportion of the auxiliary agent is 2%-4%; and the proportion of the defoaming agent is 0.5%-1%.

2. The fingerprint recognition component according to claim 1, characterized in that: The thermoplastic resin is 2,2'-[(1-methylethylene)bis(4,1-phenylenecarboxaldehyde)]dioxirane polymer; the solvent is a divalent acid ester; the auxiliary agent is a leveling agent; and the defoaming agent is silicone oil.

3. The fingerprint recognition component according to claim 1, characterized in that: The fingerprint sensor includes a stacked TFT substrate, a piezoelectric layer and an electrode layer. The protective layer is arranged on the surface of the TFT substrate facing away from the piezoelectric layer. The TFT substrate and the electrode layer are used to generate a voltage on the piezoelectric layer so that the piezoelectric layer emits an ultrasonic wave. The piezoelectric layer receives the ultrasonic wave and generates an electrical signal which is transmitted to the TFT substrate.

4. The fingerprint recognition component according to claim 3, characterized in that: The fingerprint recognition component also includes a circuit board and a driving chip. The circuit board is connected to the TFT substrate and the electrode layer, and the driving chip is connected to the circuit board.

5. The fingerprint recognition component according to claim 4, characterized in that: The end of the electrode layer extends to the surface of the TFT substrate, the circuit board is connected to the TFT substrate and the end of the electrode layer, and the circuit board is located on the side of the TFT substrate facing the piezoelectric layer, and the driving chip is arranged on the surface of the circuit board facing away from the TFT substrate.

6. The fingerprint recognition component according to claim 5, characterized in that: The fingerprint sensor also includes a DAF layer and a bonding layer stacked on the electrode layer; the bonding layer is used to bond with the cover assembly; the DAF layer is used to raise the height of the fingerprint sensor to avoid interference between the driver chip and the cover assembly.

7. An electronic device, characterized in that: It comprises a cover assembly and a fingerprint recognition assembly as described in any one of claims 1 to 6, wherein the fingerprint recognition assembly is arranged on the inner surface of the cover assembly relative to the outer surface, the outer surface of the cover assembly is used to contact with a finger, the fingerprint recognition assembly emits ultrasonic waves that pass through the cover assembly and are reflected at the fingerprint of the finger and received by the fingerprint recognition assembly.

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