CN111417295A - Conductive foam, ultrasonic fingerprint module, display screen assembly and electronic equipment - Google Patents
Conductive foam, ultrasonic fingerprint module, display screen assembly and electronic equipment Download PDFInfo
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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- G—PHYSICS
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- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
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- C08K2003/085—Copper
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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Abstract
The invention relates to a conductive foam, an ultrasonic fingerprint module, a display screen assembly and electronic equipment, wherein the conductive foam comprises the following components in percentage by mass which are uniformly mixed: 1.5-2.5% of carbon powder, 3-5% of copper powder, 3-5% of nickel powder and the balance of resin, wherein the particle size of the carbon powder is less than or equal to 0.005mm, the particle size of the copper powder is less than or equal to 0.01mm, and the particle size of the nickel powder is less than or equal to 0.01 mm. According to the invention, the shielding layer can be manufactured by the conductive foam, the shielding layer can be attached to the substrate in the ultrasonic fingerprint module, when the ultrasonic fingerprint module works, the shielding layer can reflect the ultrasonic wave emitted by the piezoelectric layer towards one side of the substrate, and the reflected ultrasonic wave and the ultrasonic wave emitted by the piezoelectric layer towards one side of the electrode layer can form resonance, so that the signal intensity of the ultrasonic wave for collecting fingerprint images is enhanced, and the collected fingerprint images are clearer. In addition, the shielding layer also has a better electromagnetic shielding effect, and can realize EMI protection.
Description
Technical Field
The invention relates to the technical field of fingerprint identification, in particular to conductive foam, an ultrasonic fingerprint module, a display screen assembly and electronic equipment.
Background
In the correlation technique, the ultrasonic fingerprint module uses glue to paste and locates electronic equipment's display panel to can make display panel have the fingerprint identification function. However, ultrasonic wave fingerprint module during operation will radiate a large amount of electromagnetic waves very easily, becomes the radiation interference source, if do not carry out EMI protection to ultrasonic wave fingerprint module, not only influences ultrasonic wave fingerprint module self performance, if probably reduce signal intensity and make the fingerprint image of gathering unclear, but also can produce electromagnetic interference to other electronic components in the electronic equipment, influence normal work.
Disclosure of Invention
Based on this, it is necessary to provide a conductive foam, ultrasonic fingerprint module, display screen subassembly and electronic equipment to solve the electromagnetic interference's that the electromagnetic wave that ultrasonic fingerprint module during operation radiated produced problem.
The conductive foam comprises the following components in percentage by mass which are uniformly mixed: 1.5-2.5% of carbon powder, 3-5% of copper powder, 3-5% of nickel powder and the balance of resin, wherein the particle size of the carbon powder is less than or equal to 0.005mm, the particle size of the copper powder is less than or equal to 0.01mm, and the particle size of the nickel powder is less than or equal to 0.01 mm.
Adopt above-mentioned electrically conductive bubble cotton can make the shielding layer, the shielding layer can with the laminating of the base plate in the ultrasonic wave fingerprint module, ultrasonic wave fingerprint module during operation, the shielding layer can be with the piezoelectric layer towards the ultrasonic wave reflection of base plate place one side transmission, ultrasonic wave after the reflection can form resonance with the ultrasonic wave of piezoelectric layer towards electrode layer place one side transmission, and then the ultrasonic signal intensity of the ultrasonic wave of fingerprint image is gathered in the reinforcing for the fingerprint image of gathering is more clear. In addition, the shielding layer also has a better electromagnetic shielding effect, and can realize EMI protection.
In one embodiment, the mass percentage of the carbon powder is 2% -2.5%. Therefore, the carbon powder with the proportion has small influence on the foaming of the conductive foam under the condition that the conductive foam has good conductive effect.
In one embodiment, the particle size of the carbon powder is less than or equal to 0.001 mm. So, the shielding layer of the cotton preparation of electrically conductive bubble that the carbon powder formed under this particle diameter range value can promote the SNR value of ultrasonic wave fingerprint module for the fingerprint image of ultrasonic wave fingerprint module collection is more clear.
In one embodiment, the mass percentage of the copper powder is 3% -4%. Therefore, the copper powder with the proportion does not excessively increase the surface impedance value of the conductive foam, and has small influence on the foaming of the conductive foam.
In one embodiment, the particle size of the copper powder is less than or equal to 0.005 mm. So, the shielding layer of the cotton preparation of electrically conductive bubble that the copper powder under this particle diameter range value formed can promote the SNR value of ultrasonic wave fingerprint module for the fingerprint image of ultrasonic wave fingerprint module collection is more clear.
In one embodiment, the nickel powder is 3 to 4% by mass. Thus, the nickel powder in the ratio does not excessively increase the surface resistance value of the conductive foam, and has little influence on the foaming of the conductive foam.
In one embodiment, the nickel powder has a particle size of 0.005mm or less. So, the shielding layer of the cotton preparation of conducting foam that nickel powder formed under this particle diameter range value can promote the SNR value of ultrasonic wave fingerprint module for the fingerprint image of ultrasonic wave fingerprint module collection is more clear.
In one embodiment, the density of the conductive foam is less than or equal to 18kg/m3. Therefore, the impedance value of the conductive foam in the density range is closer to that of air, the difference between the acoustic impedances of the shielding layer made of the conductive foam and the substrate of the ultrasonic fingerprint module is large, and ultrasonic signals can be reflected to a great extent.
An ultrasonic fingerprint module, includes:
a substrate;
the piezoelectric layer is attached to the substrate;
the electrode layer is attached to one side, away from the substrate, of the piezoelectric layer; and
the shielding layer adopts like the cotton preparation of above-mentioned electrically conductive bubble to form, the shielding layer subsides are located the base plate deviates from one side of piezoelectric layer, the shielding layer can ground connection in order to shield electromagnetic signal.
Above-mentioned ultrasonic wave fingerprint module, the shielding layer can be with the piezoelectric layer towards the ultrasonic reflection of base plate place one side transmission, and the ultrasonic wave after the reflection can form resonance with the ultrasonic wave of piezoelectric layer towards the transmission of electrode layer place one side, and then strengthens gathering the ultrasonic signal intensity of fingerprint image for the fingerprint image of gathering is more clear. In addition, the shielding layer also has a better electromagnetic shielding effect, and can realize EMI protection.
In one embodiment, the ultrasonic fingerprint module comprises a circuit board, the circuit board is electrically connected with the substrate and the electrode layer, and the shielding layer is electrically connected with the circuit board so as to realize the grounding of the shielding layer through the circuit board. So, the electrode layer can receive and dispatch the ultrasonic wave under the circuit board, and the shielding layer is connected to the circuit board and can be realized the convenient and quick ground connection of shielding layer, and then realizes EMI protection.
A display screen assembly, comprising:
a display panel;
the adhesive layer is arranged on the display panel; and
above-mentioned ultrasonic fingerprint module, the electrode layer passes through the viscose layer pastes and locates display panel, the piezoelectric layer can launch and pierce through display panel's ultrasonic wave and receive the ultrasonic wave of reflection back.
Above-mentioned display screen subassembly, the shielding layer can be with the piezoelectric layer towards the ultrasonic reflection of base plate place one side transmission, and the ultrasonic wave after the reflection can form resonance with the ultrasonic wave of piezoelectric layer towards the transmission of electrode layer place one side, and then strengthens gathering the ultrasonic signal intensity of fingerprint image for the fingerprint image of gathering is more clear. In addition, the shielding layer also has a better electromagnetic shielding effect, and can realize EMI protection.
In one embodiment, the display screen assembly comprises a protective cover plate, and the protective cover plate is connected with one side of the display panel, which faces away from the adhesive layer. Thus, the protective cover plate can enhance the structural strength.
In one embodiment, the adhesive layer is a black adhesive layer. Therefore, the black glue layer can prevent the display panel from light leakage to cause heterochromous, and the black glue layer and the display panel can form an integral black effect easily.
An electronic device, comprising:
a terminal body; and
the display screen assembly is connected with the terminal body.
Above-mentioned electronic equipment, clear even fingerprint image can be gathered to ultrasonic wave fingerprint module.
Drawings
Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application;
FIG. 2 is a schematic structural view of the display screen assembly of FIG. 1;
FIG. 3 is a fingerprint image of software testing using ultrasonic fingerprint function.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, the electronic device 10 will be described with reference to a smart phone as an example. Those skilled in the art will readily understand that the electronic device 10 of the present application may be any device having communication and storage functions, such as a smart terminal, for example, a smart phone, a tablet computer, a notebook computer, a mobile phone, a video phone, a digital still camera, an electronic book reader, a Portable Multimedia Player (PMP), a mobile medical device, etc., and the representation of the electronic device 10 is not limited herein. Of course, wearable devices such as smartwatches are also applicable to the electronic device 10 according to the embodiments of the present application.
The electronic device 10 includes a terminal body 11 and a display screen assembly 12 connected to the terminal body 11. In an embodiment, the terminal body 11 includes a middle frame 13 and a rear cover 14, the display screen assembly 12 and the rear cover 14 are respectively connected to two opposite sides of the middle frame 13 and enclose to form an accommodating space, the accommodating space may be used to mount devices such as a main board and a power supply of the electronic device 10, and the middle frame 13 and the rear cover 14 may be integrally formed or detachably connected. The side of the display screen assembly 12 facing away from the rear cover 14 includes a displayable region 121, and the displayable region 121 may form all or part of the side of the display screen assembly 12 facing away from the rear cover 14, and the displayable region 121 is used for displaying image information.
Referring to fig. 2, in an embodiment, the display panel assembly 12 includes a display panel 100 and a protective cover 200, the protective cover 200 is connected to a side of the display panel 100 facing away from the rear cover 14, the protective cover 200 may be a glass cover or a plastic cover for protecting the display panel 100 from external interference, and the displayable region 121 may be formed on all or a portion of the side of the protective cover 200 facing away from the rear cover 14. Of course, the protective cover 200 may be omitted regardless of the structural strength of the display panel 100. In an embodiment, the light shielding layer 110 is disposed around the display panel 100, the light shielding layer 110 is attached to the protective cover 200, the light shielding layer 110 may be black graphite, and the black graphite may be formed on the protective cover 200 by printing to absorb light around the display panel 100, so as to shield the devices inside the receiving space.
In one embodiment, the Display panel 100 may employ a L CD (L acquired Crystal Display, liquid Crystal Display) screen for displaying information, and the L CD screen may be a TFT (Thin Film Transistor) screen, an IPS (In-Plane Switching) screen, or an S L1 CD (split L2 acquired Crystal Display, spliced lcd) screen, In another embodiment, the Display panel 100 may employ an O L ED (Organic L light-Emitting Diode, Organic light Display) screen for displaying information, and the O L ED screen may be an AMO L ED (Active Matrix Organic L light Emitting Diode, Active Matrix Organic light Emitting Diode) screen, or a Super L (Super Active Matrix Organic light Emitting Diode) screen, which is no longer Emitting light (positive Matrix Organic 637 ED 7 light Emitting Diode, Super Active Matrix Organic light Emitting Diode, Super luminescent Diode, or Super luminescent Diode screen.
With continued reference to fig. 2, in an embodiment, the display screen assembly 12 includes an ultrasonic fingerprint module 300, and the ultrasonic fingerprint module 300 is disposed in the accommodating space and located below the display panel 100 shown in the drawing of fig. 2. Specifically, in the process of manufacturing the electronic device 10 of the present application, the ultrasonic fingerprint module 300 can be manufactured first, and after the manufacturing is completed, the ultrasonic fingerprint module 300 is attached to the bottom of the display panel 100.
Specifically, the ultrasonic fingerprint module 300 can compare the collected fingerprint with the standard fingerprint stored in the database. It will be appreciated that a standard fingerprint refers to the correct fingerprint that the user has stored in the database in advance. The controller is disposed inside the electronic device 10, and the controller may be a central processing unit of the electronic device 10, and the controller is electrically connected to the ultrasonic fingerprint module 300. At this time, the ultrasonic fingerprint module 300 can send the comparison result to the controller, and the controller controls whether the display panel 100 is started or not according to the comparison result, or controls whether the application software in the display panel 100 confirms payment or not. For example, when the fingerprint that ultrasonic fingerprint module 300 gathered is identical with the standard fingerprint, ultrasonic fingerprint module 300 sends the comparison result to the controller, and controller control display panel 100 lights the start-up. When the fingerprint that ultrasonic fingerprint module 300 gathered and standard fingerprint do not coincide, ultrasonic fingerprint module 300 will compare the result and send for the controller, and controller control display panel 100 closes. The fingerprint that gathers when ultrasonic fingerprint module 300 is the characteristic information of user's fingerprint, at this moment, through the characteristic information of ultrasonic fingerprint module 300 collection user's fingerprint to compare the characteristic information of the fingerprint of gathering with the standard characteristic information in the database.
Above-mentioned electronic equipment 10, after user's finger contact is at display panel 100, can produce the reflection after the ultrasonic wave that is transmitted by ultrasonic wave fingerprint module 300 passes display panel 100, and ultrasonic wave fingerprint module 300 can carry out fingerprint identification according to the ultrasonic wave of reflection, has realized fingerprint identification under the screen. Since the ultrasonic fingerprint module 300 does not need to be disposed in the frame of the electronic device 10, the area of the visible area of the electronic device 10 is increased.
With continued reference to fig. 2, in one embodiment, the ultrasonic fingerprint module 300 includes a substrate 310, a piezoelectric layer 320, an electrode layer 330, and a circuit board 340. The substrate 310 may be a TFT substrate, and the TFT substrate includes a base layer, a plurality of thin film transistors arranged in an array manner on the base layer, and a circuit on the base layer for connecting the thin film transistors. The TFT substrate may amplify an electric signal. Specifically, the TFT substrate may use a thin film as a base layer, for example, when the display panel 100 is a flexible panel, the TFT substrate using a thin film as a base layer can meet the flexibility requirement of the whole electronic device 10.
The piezoelectric layer 320 is attached to the substrate 310, the piezoelectric layer 320 is made of a piezoelectric material and is used for emitting and receiving ultrasonic waves by a piezoelectric effect, the material of the piezoelectric layer 320 is a ferroelectric polymer, for example, the material of the piezoelectric layer 320 may be P (VDF-TrFE) (polymer of polyvinylidene chloride and trifluoroethylene). It is to be understood that the material of the piezoelectric layer 320 is not limited to the above-mentioned materials, and for example, the material of the piezoelectric layer 320 may also be a homopolymer of polyvinylidene chloride (PVDC), a copolymer of polyvinylidene chloride, a homopolymer of polytetrafluoroethylene, a copolymer of polytetrafluoroethylene, vinylidene chloride or diisopropylamine bromide (DTPAB), or the like.
The electrode layer 330 is attached to a side of the piezoelectric layer 320 facing away from the substrate 310, and the electrode layer 330 and the substrate 310 cooperate to accommodate the piezoelectric layer 320. The material of the electrode layer 330 may be silver, and in a specific manufacturing process, the electrode layer 330 may be manufactured by screen printing silver paste on one side of the piezoelectric layer 320 and then sintering. In the embodiments of the present application, the electrode layer 330 is attached to the inner surface of the display panel 100, that is, the electrode layer 330 is attached to a side of the display panel 100 away from the protective cover 200. In an embodiment, the display panel assembly 12 includes an adhesive layer 400, the electrode layer 330 is attached to the display panel 100 through the adhesive layer 400, and the adhesive layer 400 may be a double-sided adhesive tape. In one embodiment, the adhesive layer 400 is a black adhesive layer, which can prevent the display panel 100 from light leakage to cause different colors, and is easy to form an integrated black effect with the display panel 100.
The circuit board 340 is electrically connected to the substrate 310, and the circuit board 340 is further electrically connected to the electrode layer 330. For example, fig. 2 shows that the circuit board 340 is electrically connected to the substrate 310 through the first anisotropic conductive adhesive 301, and the circuit board 340 is further electrically connected to the electrode layer 330 through the second anisotropic conductive adhesive 302. The circuit board 340 may be a flexible circuit board, and the technical feature of the circuit board 340 may be applied to other embodiments. When the display panel assembly 12 is specifically assembled, the circuit board 340 may be placed outside a path through which the ultrasonic wave is conducted to the outer surface of the display panel 100, that is, the ultrasonic wave does not pass through the circuit board 340 in the process of conducting to the contact object, so that the influence of the circuit board 340 on the conduction of the ultrasonic wave can be avoided.
In addition, a driving chip, such as an asic (application specific Integrated circuit) chip, is disposed on the circuit board 340. The driving chip provides a control signal to the piezoelectric layer 320, for example, sends a high frequency electric signal to the piezoelectric layer 320, so that the piezoelectric layer 320 emits ultrasonic waves. And the driving chip also receives an electrical signal converted from the reflected ultrasonic waves by the piezoelectric layer 320 to identify the fingerprint.
The substrate 310 and the electrode layer 330 are electrically connected to the driving chip, for example, as shown in fig. 2, the circuit board 340 may be disposed on one side of the piezoelectric layer 320 and the electrode layer 330, and electrically connected to the substrate 310 and the electrode layer 330, respectively, and the circuit board 340 is mounted in such a way as to avoid interference with the ultrasonic wave conduction.
The working principle of the ultrasonic fingerprint module 300 is as follows: when performing fingerprint identification, a user places a finger on the outer surface of the display panel 100, the driving chip applies a corresponding high-frequency electrical signal to the electrode layer 330 through the second anisotropic conductive adhesive 302, and simultaneously applies a high-frequency electrical signal to the substrate 310 through the first anisotropic conductive adhesive 301, and the piezoelectric layer 320 is activated under excitation of the electrode layer 330 and the substrate 310, so that the piezoelectric layer 320 emits ultrasonic waves. The ultrasonic wave propagates upward until reaching the outer surface of the display panel 100 and is reflected by the finger of the user, and then the piezoelectric layer 320 receives the reflected ultrasonic wave and converts the ultrasonic wave into an electrical signal, and the electrical signal is transmitted to the driving chip through the substrate 310 and is converted into an image after being processed (for example, amplified) correspondingly, so as to identify the fingerprint. Due to the difference of the skin and the air to the ultrasonic wave acoustic impedance, the positions of fingerprint ridges and fingerprint valleys can be distinguished, and the fingerprint of the user can be collected according to the difference of the reflected ultrasonic waves.
It should be noted that the circuit board 340 in the ultrasonic fingerprint module 300 according to each embodiment of the present disclosure may be omitted, and at this time, in order to realize the function of collecting fingerprints by the ultrasonic fingerprint module 300, the substrate 310 and the electrode layer 330 may be directly electrically connected to a circuit main board in the electronic device 10.
Although the ultrasonic fingerprint module 300 can realize the identification of fingerprints under the screen, the ultrasonic fingerprint module 300 emits ultrasonic waves under the condition of high frequency and high voltage, so that a large amount of electromagnetic waves are easily generated and become radiation interference sources. If do not carry out EMI protection processing to ultrasonic wave fingerprint module 300, influence the self performance of ultrasonic wave fingerprint module 300 easily, for example may reduce the signal strength (SNR value) of ultrasonic wave fingerprint module 300, produce noise etc.. In addition, the electromagnetic wave that ultrasonic wave fingerprint module 300 radiated away will influence other electronic components's work. Based on this, in an embodiment, the ultrasonic fingerprint module 300 further includes a shielding layer 350.
The shielding layer 350 is attached to one side, away from the piezoelectric layer 320, of the substrate 310, the shielding layer 350 can reflect the ultrasonic waves emitted from the piezoelectric layer 320 towards one side, where the substrate 310 is located, the ultrasonic waves after reflection and the ultrasonic waves emitted from the piezoelectric layer 320 towards one side, where the electrode layer 330 is located, can form resonance, and then the signal intensity of the ultrasonic waves for collecting fingerprint images is enhanced, so that the collected fingerprint images are clearer. In addition, shielding layer 350 can ground connection in order to realize EMI shielding protection, improves the fingerprint image quality that ultrasonic wave fingerprint module 300 gathered. In one embodiment, the shielding layer 350 is electrically connected to the circuit board 340, and the shielding layer 350 may be specifically connected to a bare copper area of the circuit board 340 by a ground line, so as to realize the grounding of the shielding layer 350 through the circuit board 340. For example, fig. 2 illustrates shield layer 350 connected to a bare copper area ground of circuit board 340 via conductor 360, and conductor 340 may be a conductive cloth or a metal tape (e.g., a copper foil tape). The shielding layer 350 may also be ground connected to the bare copper area of the display panel 100 to achieve grounding of the shielding layer 350. Or the shielding layer 350 may be connected with the terminal body 11 (e.g., the middle frame 13 or the rear cover 14) to realize grounding of the shielding layer 350.
It should be noted that the shielding layer 350 in the embodiments of the present application is made of conductive foam. The conductive foam comprises the following components in percentage by mass which are uniformly mixed: 1.5-2.5% of carbon powder, 3-5% of copper powder, 3-5% of nickel powder and the balance of resin, wherein the particle size of the carbon powder is less than or equal to 0.005mm, the particle size of the copper powder is less than or equal to 0.01mm, and the particle size of the nickel powder is less than or equal to 0.01 mm. The resin can be polyurethane or acrylic resin, for example, and in order to obtain the conductive foam, the carbon powder, the copper powder and the nickel powder with the components and the particle size range are added into the resin to be uniformly mixed with the resin, so that the conductive foam is formed after the resin is foamed. And the formed conductive foam can realize all-dimensional conductivity, namely the conductive foam can conduct electricity in X, Y, Z three directions, which can be realized by uniformly filling carbon powder, copper powder and nickel powder into resin.
The carbon powder is used as a conductive material and has low conductive impedance, and the carbon powder is used for EMI protection. The performance of the fingerprint test image is affected due to the fact that the surface roughness of the shielding layer 350 formed by the conductive foam is too large, and therefore the particle size of the carbon powder is kept within 0.005 mm. Furthermore, the grain diameter of the carbon powder is less than or equal to 0.001 mm. The conductive foam with the carbon powder with the particle size can be used for preparing the shielding layer 350 with a smooth surface and small roughness, and the roughness can be that Rz is less than 0.001 mm. If the mass ratio of the carbon powder filled in the conductive foam is too low, the impedance of the surface of the formed shielding layer 350 is large, and the conductive performance requirement cannot be met, and if the mass ratio of the carbon powder is too high, the dispersion difficulty of the carbon powder in the manufacturing process of the conductive foam is increased, and the risk of agglomeration can occur. Therefore, the mass ratio of the carbon powder filled in the conductive foam is controlled to be 1.5-2.5%. Further, in one embodiment, the mass ratio of the carbon powder is controlled to be 2% -2.5%.
The copper powder and the nickel powder can further improve the conductivity of the conductive foam, and the particle size of the copper powder and the nickel powder is kept within 0.01mm in order to reduce the surface roughness of the shielding layer 350 formed by the conductive foam. In one embodiment, the particle size of the copper powder is less than or equal to 0.005mm, and the particle size of the nickel powder is less than or equal to 0.005 mm. If the mass ratio of copper powder and nickel powder of filling in the conducting foam is low excessively, the surface impedance on its surface can be great after shielding layer 350 shaping, can't satisfy the electric conductive property requirement, and if the ratio of occupying of copper powder and nickel powder is too high, then can influence the foaming process of conducting foam, be unfavorable for the foaming of conducting foam, the foaming of conducting foam receives the influence density and can not fall, the impedance value of conducting foam is great with the impedance value difference of air this moment, the shielding layer 350 of utilizing the cotton preparation of conducting foam is not big with the base plate 310 acoustic impedance difference of ultrasonic fingerprint module 300 promptly, ultrasonic signal can not be reflected well. Therefore, the mass ratio of the copper powder and the nickel powder filled in the conductive foam is controlled in a small range. In one embodiment, the mass ratio of the copper powder to the nickel powder is controlled to be 3% to 5%. Further, the mass ratio of the copper powder to the nickel powder is controlled to be 3-4%.
Adopt the shielding layer 350 of the cotton preparation of above-mentioned electrically conductive bubble in with the laminating back of the base plate 310 of ultrasonic fingerprint module 300, when ultrasonic fingerprint module 300 during operation, shielding layer 350 can be with the ultrasonic reflection of piezoelectric layer 320 towards base plate 310 place one side transmission, ultrasonic wave after the reflection can form resonance with the ultrasonic wave of piezoelectric layer 320 towards electrode layer 330 place one side transmission, and then the ultrasonic signal intensity of the ultrasonic wave of fingerprint image is gathered in the reinforcing for the fingerprint image of gathering is more clear. In addition, based on the content and particle size of the metal powder, the formed shielding layer 350 also has a good electromagnetic shielding effect, and can realize EMI protection.
To illustrate the effect of the density of the conductive foam on the sharpness of the image in the fingerprint test, refer to table 1 below, where table 1 lists the effect of the conductive foam on the sharpness of the image in the fingerprint test when the conductive foam has different densities. The fingerprint test may be performed by attaching the shielding layer 350 to the substrate 310, attaching the electrode layer 330 to the display panel 100, and attaching a real finger or a dummy finger having a fingerprint pattern to the display panel 100. The fingerprint test image definition can be obtained by measuring an SNR (signal to noise ratio), wherein the larger the SNR is, the closer to the fingerprint test image is, and the fingerprint test image definition can also be obtained by visual observation.
TABLE 1
| Experimental number | Foam density kg/m3 | SNR value | Test background |
| 1 | 90 | 2.53 | Blurring |
| 2 | 45 | 3.79 | Blurring |
| 3 | 18 | 4.53 | Blurring |
As can be seen from Table 1, the SNR value measured was larger as the density of the conductive foam was smaller. It should be noted that the SNR (signal-to-noise ratio), i.e. the output signal power of the amplifier, is a ratio of the output signal power and the noise power outputted at the same time, and is usually expressed in decibels. A higher signal-to-noise ratio of the device indicates that it produces less noise, i.e. a higher signal-to-noise ratio indicates that less noise is mixed in the signal, that the quality of the sound played back is higher, that the signal is stronger, and vice versa. Referring to fig. 3, under the influence of the shielding layer 350, the SNR of the ultrasonic fingerprint module 300 is measured by the ultrasonic fingerprint function testing software, and the signal ratio of the fingerprint ridge (the white area in the testing image shown in fig. 3) and the fingerprint valley (the black area in the testing image in fig. 3) of the fake finger is the SNR.
For experiment 3, the SNR value of experiment 3 is the largest because the smaller the density of the conductive foam is, the closer the acoustic impedance is to the air, the larger the difference between the acoustic impedance and the substrate 310 is, the ultrasonic signal is greatly reflected back, and the fingerprint test image is close to clear. But the final test results show that the test image of experiment 3 is still very blurred and the test background is very dirty. This is because the definition of the test image in the three experiments is affected by the mass ratio and the particle size of the carbon powder, the copper powder and the nickel powder filled in the conductive foam.
Based on this, in order to illustrate the influence of the mass ratio and particle size of the carbon powder, copper powder and nickel powder, a density of 18kg/m was used in the present application2The conductive foam is subjected to multiple groups of experimental verification (when in practical application, the density of the conductive foam can be less than or equal to 18kg/m2) The definition of the fingerprint image collected by the ultrasonic fingerprint module 200 during the EMI protection is verified by the surface impedance and the electromagnetic shielding performance of the shielding layer 350 formed by the conductive foam.
It should be noted that the electromagnetic shielding performance of the shielding layer 350 formed by the conductive foam of the present application can be measured by the shielding effectiveness SE, which is defined as follows:
SE＝20lg(E1/E2)(dB)
in the formula, E1 represents the field strength when no shield is present, E2 represents the field strength when a shield is present, and if the field strength is used in the shield effectiveness calculation formula, it is referred to as the magnetic field shield effectiveness, and if the field strength is used in the shield effectiveness calculation formula, it is referred to as the electric field shield effectiveness, and the unit of the shield effectiveness is decibels (dB).
Please refer to the group comparative examples and examples listed in table 2 below.
TABLE 2
The results in table 2 show that the shielding layer 350 formed by the conductive foam of examples 1 to 12 has lower surface impedance and higher shielding performance, and the measured fingerprint test image has better definition (high SNR value). Wherein, when the particle size of the metal powder is 0.0001mm, the metal powder is closest to 0 in the value range.
Comparing the embodiment 1 and the embodiment 2 with the comparative example 1, it can be seen that when the content of the carbon powder is 1.5-2.5%, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
Comparing examples 3 and 4 with comparative example 2, it can be seen that when the copper powder content is 3% -5%, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
Comparing examples 5 and 6 with comparative example 3, it can be seen that when the nickel powder content is 3% -5%, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
Comparing examples 7 and 8 with comparative example 4, it can be seen that when the particle size of the carbon powder is less than or equal to 0.005mm, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
Comparing examples 9 and 10 with comparative example 5, it can be seen that when the particle size of the copper powder is less than or equal to 0.01mm, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
Comparing examples 11 and 12 with comparative example 6, it can be seen that when the particle size of the nickel powder is less than or equal to 0.01mm, the prepared shielding layer 350 has low surface impedance, high shielding performance and small influence on the fingerprint test process.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The conductive foam is characterized by comprising the following components in percentage by mass which are uniformly mixed: 1.5-2.5% of carbon powder, 3-5% of copper powder, 3-5% of nickel powder and the balance of resin, wherein the particle size of the carbon powder is less than or equal to 0.005mm, the particle size of the copper powder is less than or equal to 0.01mm, and the particle size of the nickel powder is less than or equal to 0.01 mm.
2. The conductive foam as recited in claim 1, wherein the carbon powder is 2-2.5% by mass; and/or the particle size of the carbon powder is less than or equal to 0.001 mm.
3. The conductive foam as recited in claim 1, wherein the copper powder accounts for 3-4% by weight; and/or the particle size of the copper powder is less than or equal to 0.005 mm.
4. The conductive foam according to claim 1, wherein the nickel powder accounts for 3-4% by weight; and/or the particle size of the nickel powder is less than or equal to 0.005 mm.
5. The conductive foam of any one of claims 1 to 4, wherein the density of the conductive foam is less than or equal to 18kg/m3。
6. The utility model provides an ultrasonic fingerprint module which characterized in that includes:
a substrate;
the piezoelectric layer is attached to the substrate;
the electrode layer is attached to one side, away from the substrate, of the piezoelectric layer; and
the shielding layer is made of the conductive foam as claimed in any one of claims 1 to 5, the shielding layer is attached to one side, away from the piezoelectric layer, of the substrate, and the shielding layer can be grounded to shield electromagnetic signals.
7. The ultrasonic fingerprint module of claim 6, comprising a circuit board electrically connected to the substrate and the electrode layer, wherein the shielding layer is electrically connected to the circuit board to achieve grounding of the shielding layer through the circuit board.
8. A display screen assembly, comprising:
a display panel;
the adhesive layer is arranged on the display panel; and
the ultrasonic fingerprint module according to claim 6 or 7, wherein the electrode layer is attached to the display panel through the adhesive layer, and the piezoelectric layer is capable of emitting ultrasonic waves penetrating through the display panel and receiving reflected ultrasonic waves.
9. The display screen assembly of claim 8, wherein the display screen assembly comprises a protective cover plate connected to a side of the display panel facing away from the adhesive layer; and/or
The adhesive layer is a black adhesive layer.
10. An electronic device, comprising:
a terminal body; and
the display screen assembly of claim 8 or 9, connected with the terminal body.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010151788.1A CN111417295A (en) | 2020-03-06 | 2020-03-06 | Conductive foam, ultrasonic fingerprint module, display screen assembly and electronic equipment |
| PCT/CN2021/075723 WO2021175101A1 (en) | 2020-03-06 | 2021-02-07 | Electrically-conductive foam, ultrasonic fingerprint module, display screen assembly, and electronic apparatus |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010151788.1A CN111417295A (en) | 2020-03-06 | 2020-03-06 | Conductive foam, ultrasonic fingerprint module, display screen assembly and electronic equipment |
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| CN111417295A true CN111417295A (en) | 2020-07-14 |
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| CN202010151788.1A Pending CN111417295A (en) | 2020-03-06 | 2020-03-06 | Conductive foam, ultrasonic fingerprint module, display screen assembly and electronic equipment |
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| WO (1) | WO2021175101A1 (en) |
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| CN111914776A (en) * | 2020-08-07 | 2020-11-10 | 业泓科技(成都)有限公司 | Display device |
| CN112711150A (en) * | 2020-12-22 | 2021-04-27 | 业泓科技(成都)有限公司 | Display device |
| WO2021175101A1 (en) * | 2020-03-06 | 2021-09-10 | 欧菲光集团股份有限公司 | Electrically-conductive foam, ultrasonic fingerprint module, display screen assembly, and electronic apparatus |
| CN113762167A (en) * | 2021-09-09 | 2021-12-07 | 业泓科技(成都)有限公司 | Under-screen fingerprint identification device and electronic equipment |
| CN114927057A (en) * | 2022-03-14 | 2022-08-19 | 友达光电股份有限公司 | Display device and assembling method thereof |
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| CN115534456B (en) * | 2022-09-16 | 2024-07-05 | 苏州旺顺源光电科技有限公司 | Flame-retardant conductive foam and preparation process thereof |
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| CN113762167B (en) * | 2021-09-09 | 2024-02-27 | 业泓科技(成都)有限公司 | Under-screen fingerprint identification device and electronic equipment |
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|---|---|
| WO2021175101A1 (en) | 2021-09-10 |
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Address after: 330096 No.699 Tianxiang North Avenue, Nanchang hi tech Industrial Development Zone, Nanchang City, Jiangxi Province Applicant after: Jiangxi OMS Microelectronics Co.,Ltd. Address before: 330096 No.699 Tianxiang North Avenue, Nanchang hi tech Industrial Development Zone, Nanchang City, Jiangxi Province Applicant before: OFilm Microelectronics Technology Co.,Ltd. Address after: 330096 No.699 Tianxiang North Avenue, Nanchang hi tech Industrial Development Zone, Nanchang City, Jiangxi Province Applicant after: OFilm Microelectronics Technology Co.,Ltd. Address before: 330029 No. 1189 Jingdong Avenue, Nanchang high tech Zone, Jiangxi Applicant before: NANCHANG OFILM BIO-IDENTIFICATION TECHNOLOGY Co.,Ltd. |
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