CN210402405U

CN210402405U - Ultrasonic fingerprint module, display screen assembly and electronic equipment

Info

Publication number: CN210402405U
Application number: CN201921840705.9U
Authority: CN
Inventors: 李萍
Original assignee: Nanchang OFilm Biometric Identification Technology Co Ltd
Current assignee: Ofilm Microelectronics Technology Co ltd; Jiangxi OMS Microelectronics Co Ltd
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2020-04-24
Anticipated expiration: 2029-10-29

Abstract

The utility model discloses an ultrasonic wave fingerprint module, display screen subassembly and electronic equipment, ultrasonic wave fingerprint module includes ultrasonic detection layer and printing ink layer, the ultrasonic detection layer has the ultrasonic wave and receives the face, the printing ink layer set up in the ultrasonic detection layer is kept away from the one side that the ultrasonic wave received the face, the printing ink layer is used for right following the ultrasonic wave that the ultrasonic detection layer jetted out reflects. Through set up the printing ink layer on the ultrasonic detection layer at ultrasonic wave fingerprint module, utilize the printing ink layer can keep out and reflect ultrasonic signal and see through for the ultrasonic signal who conducts to the ultrasonic detection layer is strengthened, has improved the ultrasonic detection layer and has improved fingerprint identification efficiency to ultrasonic signal receiving efficiency.

Description

Ultrasonic fingerprint module, display screen assembly and electronic equipment

Technical Field

The utility model relates to a fingerprint identification technical field especially relates to an ultrasonic fingerprint module, display screen subassembly and electronic equipment.

Background

At present, the ultrasonic fingerprint module is compared through the ultrasonic signal that reflects back from user fingerprint valley region and the ultrasonic signal that reflects back from user fingerprint ridge region to discern user's fingerprint. However, under the condition that ultrasonic wave fingerprint module sees through ultrasonic signal easily, the ultrasonic signal intensity that leads to ultrasonic wave fingerprint module to acquire reduces, and the ultrasonic signal of the valley region that is difficult to distinguish and the ultrasonic signal difference of ridge region have reduced fingerprint identification efficiency.

SUMMERY OF THE UTILITY MODEL

An object of this application is to provide an ultrasonic fingerprint module, display screen subassembly and electronic equipment that improves fingerprint identification efficiency.

The application provides an ultrasonic fingerprint module, wherein, ultrasonic fingerprint module includes ultrasonic detection layer and printing ink layer, the ultrasonic detection layer has the ultrasonic wave and receives the face, the printing ink layer set up in the ultrasonic detection layer is kept away from the one side that the ultrasonic wave received the face, the printing ink layer is used for the follow the ultrasonic wave that the ultrasonic detection layer jetted out reflects. Utilize the printing ink layer can be to following the ultrasonic wave that the ultrasonic detection layer jetted out is to waiting to detect the fingerprint reflection for the ultrasonic signal who waits to detect the fingerprint received strengthens, has improved ultrasonic fingerprint module and has waited to detect fingerprint outgoing ultrasonic signal intensity, has improved fingerprint identification efficiency.

Wherein, the ink layer contains resin material and carbon powder particles. The printing ink layer has insulativity by utilizing resin materials so as to ensure that the printing ink layer can perform insulation protection on the ultrasonic detection layer, and the printing ink layer has the elastic modulus similar to that of a plastic sheet by utilizing the solidified resin materials so as to ensure that the printing ink layer has the ultrasonic reflection efficiency which is approximately the same as that of the plastic sheet. The carbon powder particles in the ink layer can fill gaps among the resin particles in the resin material, so that the surface roughness of the ink layer is reduced, and the surface of the ink layer is smooth.

The average particle size of the carbon powder particles is 0.5-5 microns, so that the roughness of the ink layer can be effectively reduced.

Wherein the average particle size of the carbon powder particles is 0.8-2 microns, so that the roughness of the ink layer can be further reduced to the range of 0.41-0.82 Rz/mum.

The mass ratio of the carbon powder particles in the ink layer is 2.5% -15%, so that the roughness of the ink layer can be effectively reduced.

The mass ratio of the carbon powder particles in the ink layer is 3.0% -10%, so that the roughness of the ink layer can be further reduced to the range of 0.41 Rz/mum-0.82 Rz/mum, the SNR value of the ultrasonic fingerprint module is greater than 10, and the OD value of the ultrasonic fingerprint module is greater than 4.

Wherein, the resin material is epoxy, makes the SNR value of ultrasonic wave fingerprint module can be greater than 8, improves the fingerprint identification precision of ultrasonic wave fingerprint module.

The resin material is epoxy resin with CAS number 38891-59-7, so that the SNR value of the ultrasonic fingerprint module can be greater than 10, and the fingerprint identification accuracy of the ultrasonic fingerprint module is further improved.

The ink layer further comprises a leveling agent, the leveling agent is used for improving the surface leveling property of the ink layer in the manufacturing process and improving the surface leveling property of the finally formed ink layer, and the leveling agent is used for defoaming the surface of the ink layer, controlling the surface leveling property of the ink layer and improving the surface leveling property of the ink layer, so that the surface roughness of the ink layer is effectively reduced.

The ink layer further comprises a defoaming agent, the defoaming agent is used for eliminating bubbles of the ink layer in the manufacturing process and eliminating the bubbles of the finally formed ink layer, and the defoaming agent can eliminate the performance of the ink layer for generating the bubbles in the preparation process, so that the number of the bubbles in the ink layer is reduced, and the definition of the ultrasonic fingerprint module for acquiring the fingerprint image can be improved.

Wherein, the thickness on printing ink layer is 5 microns to 30 microns for the roughness on surface on printing ink layer effectively reduces, just the fingerprint image definition that the ultrasonic wave fingerprint module acquireed effectively improves.

Wherein, the thickness of printing ink layer is 20 microns to 30 microns for the roughness on surface of printing ink layer further reduces, the fingerprint image definition that the ultrasonic wave fingerprint module was obtained further improves.

The thickness of the ink layer is 25 micrometers, so that the surface roughness of the ink layer is further reduced, and the SNR value and the LPMM value of the ultrasonic fingerprint module are more excellent.

Wherein, ultrasonic detection layer is including the substrate layer, pixel electrode layer, piezoelectric layer and the conducting electrode that stack gradually the setting, the printing ink layer set up in the conducting electrode is kept away from the one side of piezoelectric layer makes ultrasonic fingerprint module is more slim, and is convenient ultrasonic fingerprint module is integrated in electronic equipment's display screen.

The application still provides a display screen subassembly, wherein, the display screen subassembly includes display screen and above-mentioned ultrasonic fingerprint module, the display screen has the surface towards the user, ultrasonic fingerprint module is fixed in the screen of display screen or under the screen, the printing ink layer is relative the ultrasonic detection layer is kept away from the surface, ultrasonic fingerprint module can be located the display area of display screen conveniently acquires the fingerprint image at the display area of display screen.

The application also provides an electronic device, wherein, electronic device includes foretell display screen subassembly, makes electronic device can satisfy diversified fingerprint identification requirement, improves fingerprint identification efficiency.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings required for the embodiments will be briefly described below, and obviously, the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic view of an ultrasonic fingerprint module according to an embodiment of the present disclosure;

fig. 2 is another schematic view of an ultrasonic fingerprint module according to an embodiment of the present disclosure;

fig. 3 is another schematic diagram of an ultrasonic fingerprint module according to an embodiment of the present disclosure;

fig. 4 is a schematic flowchart illustrating a manufacturing method of an ultrasonic fingerprint module according to an embodiment of the present disclosure;

FIG. 5 is a schematic view of a display screen assembly provided by an embodiment of the present application;

FIG. 6 is another schematic view of a display screen assembly provided by an embodiment of the present application;

FIG. 7 is a schematic view of a display screen assembly provided in accordance with another embodiment of the present application;

FIG. 8 is another schematic view of a display screen assembly provided in accordance with another embodiment of the present application;

FIG. 9 is a schematic view of a display screen assembly provided in accordance with another embodiment of the present application;

FIG. 10 is a schematic view of a display screen assembly provided in accordance with another embodiment of the present application;

fig. 11 is a schematic cross-sectional view of an electronic device provided in an embodiment of the present application.

Detailed Description

The technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

Referring to fig. 1, the present invention provides an ultrasonic fingerprint module 100, where the ultrasonic fingerprint module 100 includes an ultrasonic detection layer 10 and an ink layer 20, the ultrasonic detection layer 10 has an ultrasonic receiving surface 11, the ink layer 20 is formed on the surface of the ultrasonic detection layer 10 away from the ultrasonic receiving surface 11, the ink layer 20 can block the ultrasonic wave from exiting from the surface away from the ultrasonic detection layer 10, and can reflect the ultrasonic signal transmitted from the ultrasonic detection layer 10 to the ultrasonic detection layer 10.

It can be understood that the ultrasonic fingerprint module 100 can detect the fingerprint of the user by using the ultrasonic signal, thereby identifying the fingerprint image of the user. The ultrasonic fingerprint module 100 may be applied to an electronic device, which may be a mobile phone, a tablet computer, a notebook computer, a media player, or a financial terminal device such as an Automated Teller Machine (ATM).

Through set up printing ink layer 20 on ultrasonic detection layer 10 at ultrasonic wave fingerprint module 100, utilize printing ink layer 20 can keep out and reflect ultrasonic signal for ultrasonic signal that ultrasonic detection layer 10 can be received strengthens, has improved ultrasonic detection layer 10 and has improved fingerprint identification efficiency to ultrasonic signal receiving efficiency.

In this embodiment, the ultrasonic detection layer 10 can transmit an ultrasonic signal and can sense the ultrasonic signal to recognize the fingerprint of the user. The ultrasonic detection layer 10 can emit a first ultrasonic signal 01 toward the side away from the ink layer 20 and a second ultrasonic signal 02 toward the ink layer 20. In ultrasonic fingerprint module 100 is applied to electronic equipment, when the user finger be close to ultrasonic fingerprint module 100 deviates from printing ink layer 20 one side, first ultrasonic signal 01 is towards user's fingerprint transmission, second ultrasonic signal 02 warp printing ink layer 20 keeps out and towards ultrasonic detection layer 10 reflects back and forms third ultrasonic signal 03. The third ultrasonic signal 03 is also emitted towards the user fingerprint. The third ultrasonic signal 03 and the first ultrasonic signal 01 can be emitted toward the fingerprint of the user after forming resonance.

It can be understood that the fingerprint of the user receives the ultrasonic signal after resonance and then reflects the ultrasonic signal back to the ultrasonic detection layer 10, so that the fingerprint detection signal sensed by the ultrasonic detection layer 10 is enhanced. The ultrasonic detection layer 10 receives an ultrasonic detection signal through the ultrasonic receiving surface 11, and acquires a user fingerprint image. Because the user fingerprint has a wave area and a valley area, the wave area and the valley area have different reflectivity to the ultrasonic initial signal, and the ultrasonic detection signal reflected by the user fingerprint has a wave signal capable of reflecting the wave area and a valley signal capable of reflecting the valley area. And comparing the wave signal with the valley signal, and processing the wave signal and the valley signal after acquiring the difference data of the wave signal and the valley signal so as to acquire the fingerprint image of the user.

In this embodiment, the ultrasonic detection layer 10 forms a fingerprint recognition area in an area covered by the ultrasonic fingerprint module 100. Ultrasonic fingerprint module 100 adopts large-area ultrasonic detection layer 10, makes the length dimension of the fingerprint identification area of ultrasonic fingerprint module 100 can be 30mm, width dimension can be 20 mm. Ultrasonic wave fingerprint module 100 has the bigger fingerprint identification area than the present fingerprint module that has less fingerprint identification area, can be applicable to the fingerprint unblock scene of large tracts of land to and can realize the blind unblock of fingerprint, and conveniently utilize fingerprint unblock control electronic equipment program to start etc.. For example, ultrasonic fingerprint module 100 is applicable to more in the comprehensive screen cell-phone, satisfies large tracts of land fingerprint identification demand. Of course, in other embodiments, the length of the fingerprint identification area of the ultrasonic fingerprint module 100 may also be 40mm or more than 40mm, and the width dimension may be 30mm or more than 30 mm.

In this embodiment, because the fingerprint identification regional increase of fingerprint identification module 100 leads to the area increase of fingerprint detection layer 10, but printing ink layer 20 can adopt printing technology, or vacuum evaporation technology, or spraying technology etc. large tracts of land processing technology shaping in on the fingerprint detection layer 10 to avoid the interface gassing of printing ink layer 20 and fingerprint detection layer 10, avoid leading to ultrasonic reflection efficiency inhomogeneous because of the bubble, thereby guaranteed fingerprint identification's validity. The ink layer 20 may be an insulating ink. The side, far away from the ultrasonic detection layer, of the ink layer 20 is in contact with the air, an ultrasonic reflection surface is formed on an interface between the ink layer 20 and the air, and the interface between the ink layer 20 and the air has higher ultrasonic reflectivity by utilizing the difference between the acoustic impedance of the ink layer 20 and the acoustic impedance of the air, wherein the difference is larger. The acoustic impedance of the ink layer 20 is proportional to the elastic modulus, so that the larger the elastic modulus of the ink layer 20 is, the larger the acoustic impedance of the ink layer 20 is. In this embodiment, the elastic modulus of the ink layer 20 is substantially equal to that of the plastic film, so that the ink layer 20 has a good shielding effect on the ultrasonic signal, and the interface of the ink layer 20 contacting with air has a good reflection efficiency on the ultrasonic wave. The ink layer 20 resists and reflects the ultrasonic signal emitted by the ultrasonic detection layer 10, so that the ultrasonic wave received by the user fingerprint is strengthened, the ultrasonic detection layer 10 receives the ultrasonic wave strengthened reflected by the user fingerprint, and the identification efficiency of the ultrasonic detection layer 10 is improved. The ink layer 20 also has a protection effect with the ultrasonic detection layer 10, so as to ensure the safety of the ultrasonic detection layer 10. The ink layer 20 also has a function of resisting ultrasonic waves transmitted from outside air, so that ultrasonic signals of an external environment are resisted, the ultrasonic detection layer 10 is prevented from being interfered by environmental ultrasonic waves to identify the ultrasonic signals reflected from the user fingerprint, and the accuracy of identifying the user fingerprint by the ultrasonic detection layer 10 is ensured.

It is understood that the ink layer 20 is provided with a resin material, for example, the ink layer 20 contains any one or more of acrylic resin, polyester resin, isocyanate resin, phenoxy resin, and epoxy resin. In a preferred embodiment, the ink layer 20 contains an epoxy resin material. The ink layer 20 is made of a resin material having an insulating property to ensure that the ink layer 20 can perform an insulating protection function on the ultrasonic detection layer 10, and the cured resin material has an elastic modulus similar to that of a plastic sheet to ensure that the ink layer 20 has an ultrasonic reflection efficiency substantially the same as that of the plastic sheet.

In the process of using the printing ink layer 20, the printing ink layer 20 made of various different materials can be formed on the multiple groups of fingerprint detection layers 10 through a screen printing process so as to obtain samples of the multiple groups of ultrasonic fingerprint detection modules 100. SNR (SIGNAL to noise ratio) value detection is carried out on samples of the multiple groups of ultrasonic fingerprint detection modules 100 to obtain the average SNR value of the samples of the multiple groups of ultrasonic fingerprint detection modules 100, and then the material for the ink layer 20 with the optimal average SNR value is selected after the multiple groups of average SNR values are compared. The SNR value can be tested by an ultrasonic fingerprint testing instrument.

Specifically, a first set of samples of the ultrasonic fingerprint module 100 is provided, and the ink layer 20 of the set of samples is made of acrylic resin. A second set of samples of the ultrasonic fingerprint module 100 is provided, and the ink layer 20 of the set of samples is made of polyester resin. A third group of samples of the ultrasonic fingerprint module 100 is provided, and the ink layer 20 of the group of samples adopts mixed resin of acrylic resin, isocyanate resin and polyester resin. A fourth set of samples of the ultrasonic fingerprint module 100 is provided, and the ink layer 20 of the set of samples adopts phenoxy resin. Providing a fifth set of samples of the ultrasonic fingerprint module 100, wherein the ink layer 20 of the set of samples is made of epoxy resin 1, and the epoxy resin 1 can be conventional epoxy resin. Providing a sixth group of samples of the ultrasonic fingerprint module 100, wherein the ink layer 20 of the group of samples adopts epoxy resin 2, the specification of the epoxy resin 2 is different from that of the epoxy resin 1, and the CAS number of the epoxy resin 2 is 38891-59-7. The SNR values of the samples in the first group are 8.10, 8.75, 8.85, 7.48, 7.45, 7.89, 8.16, respectively. The SNR values of the samples in the second group are 3.77, 3.89, 3.87, 3.22, 3.93, 4.08 and 3.61 respectively. The SNR values of the samples in the third group are 7.38, 8.18, 7.09, 7.75, 7.39, 6.84 and 7.02 respectively. The SNR values of the samples in the fourth group were 8.54, 8.65, 9.01, 8.76, 7.68, 8.68, 8.46, respectively. The SNR values of the samples in the fifth group are 8.89, 8.33, 8.07, 9.69, 8.94 and 9.40 respectively. The SNR values of the samples in the sixth group were 10.33, 9.63, 10.47, 10.99, 10.56, 10.03, 10.32, respectively. Further, the SNR average values of the first, second, third, fourth, fifth, and sixth groups of samples were 8.10, 3.77, 7.38, 8.54, 8.89, and 10.33, respectively. It can be seen that the printing ink layer 20 of the ultrasonic fingerprint module 100 sample of the sixth group adopts epoxy resin 2, and the average value of the SNR is the best, so that the printing ink layer 20 is made of epoxy resin 2, and the fingerprint identification efficiency of the ultrasonic fingerprint module 100 is better. Among them, epoxy resin 1 is different from epoxy resin 2 in specification. Specifically, the CAS number of the epoxy resin 2 is 38891-59-7.

The ultrasonic detection layer 10 has a detection layer bottom surface 12 opposite to the ultrasonic receiving surface 11, and the ink layer 20 is formed on the detection layer bottom surface 12 through a printing process. The ink layer 20 may be formed on the bottom surface 12 of the detection layer by a TFT (Thin film transistor) printing process. Utilize printing ink layer 20 can be through printing technology shaping for printing ink layer 20 can the large tracts of land shaping, and the one shot press shaping is a plurality of ultrasonic wave fingerprint module 100 to obtain ultrasonic wave fingerprint module 100 in batches after tailorring, improve production efficiency. Specifically, at first the ultrasonic detection layer 10 of shaping large tracts of land, then print the printing ink layer 20 of shaping large tracts of land on the ultrasonic detection layer 10 of large tracts of land, then cut out the ultrasonic detection layer 10 of large tracts of land and the printing ink layer 20 of large tracts of land in the lump and form a plurality of ultrasonic fingerprint modules 100, realize the quick batch production of ultrasonic fingerprint module 100, reduction in production cost raises the efficiency.

Further, the ink layer 20 is formed by adding carbon powder particles to a resin material, so that the ink layer 20 presents a black appearance effect.

In this embodiment, a resin material and carbon powder are mixed to form liquid ink, and then the liquid ink is formed on the ultrasonic fingerprint detection layer 10 by a screen printing process and cured to form the ink layer 20. The elastic modulus of the ink layer 20 is determined according to the frequency of the ultrasonic waves emitted from the ultrasonic detection layer 10, so that the elastic modulus of the ink layer 20 matches the frequency of the ultrasonic waves. Through setting up the elastic modulus of printing ink layer 20 for printing ink layer 20 can keep out and reflect ultrasonic signal, in order to realize the fingerprint identification efficiency of ultrasonic fingerprint module 100 improves. The ink layer 20 contains black carbon powder, and the ink layer 20 presents a black appearance visual effect, so that the ink layer 20 can block visible light from transmitting, namely the ink layer 20 can cover the ultrasonic fingerprint detection layer 10, so that the appearance defects of the ultrasonic fingerprint detection layer 10 are invisible, and the appearance performance of the ultrasonic fingerprint module 100 is improved. The ink layer 20 may be formed by printing a liquid printing material to form a layer structure and then performing a curing process. Specifically, first, a liquid resin material and a black carbon powder material mixed with the liquid resin material are provided. Then, a liquid resin material mixed with a black carbon powder material is printed and molded on the bottom surface 12 of the detection layer of the ultrasonic detection layer 10 by a printing device. Finally, the liquid ink layer 20 in a layered structure is cured to obtain a solid ink layer 20. Of course, in other embodiments, the ink layer 20 may be made of insulating paste and white carbon powder, red carbon powder, or green carbon powder mixed with the insulating paste. The ink layer 20 may also be made of other materials with ultrasonic wave shielding property mixed with colored particles. Of course, in other embodiments, the ink layer 20 may also be a transparent layer, so that the ultrasonic fingerprint module 100 is integrated in a display screen, and the display effect of the display screen is ensured.

In this embodiment, the carbon powder particles in the ink layer 20 can fill gaps between resin particles in the resin material, so that the surface roughness of the ink layer 20 is reduced, and the surface of the ink layer 20 is smooth.

In particular, the ink layer 20 has a first surface 201 remote from the fingerprint detection layer 10. The first surface 201 is in contact with air. The first surface 201 is smoothly arranged, and the roughness of the first surface 201 is 0.2 Rz/mum-6.0 Rz/mum. For example, the roughness of the first surface 201 may be 0.41Rz/μm, or 0.68Rz/μm, or 4.76Rz/μm, or 5.25Rz/μm. The ink layer 20 has a second surface 202 opposite the first surface 201. The second surface 202 is attached to the fingerprint detection layer 10. The second surface 202 is smoothly arranged, and the roughness of the second surface is 0.2Rz/μm to 6.0Rz/μm. For example, the roughness of the first surface 201 may be 0.41Rz/μm, or 0.68Rz/μm, or 4.76Rz/μm, or 5.25Rz/μm. The smaller the roughness of the first surface 201 is, the smaller the degree of unevenness of the first surface 201 is, that is, the smoother the first surface is, the more difficult the ultrasonic wave is to generate diffuse reflection on the first surface 201, the more the reflection direction of the ultrasonic wave on the first surface 201 tends to be consistent, the smaller the ultrasonic interference signal received by the ultrasonic detection layer 10 is, and the fingerprint identification definition of the ultrasonic fingerprint module 100 is improved. Similarly, the smaller the roughness of second surface 202, the ultrasonic wave is in the process second surface 202 is difficult diffuse reflection more, has improved ultrasonic fingerprint module 100's fingerprint identification efficiency.

It is understood that the larger the average particle size of the carbon powder particles in the ink layer 20, the easier the roughness of the first surface 201 and the roughness of the second surface 202 of the ink layer 20 are increased, the easier the first surface 201 forms diffuse reflection to the ultrasonic waves, and the second surface 202 forms diffuse reflection to the ultrasonic waves. Therefore, by setting the average particle size of the carbon powder particles in the ink layer 20 and setting the proportion of the carbon powder particles in the ink layer 20, the roughness of the first surface 201 and the roughness of the second surface 202 can be improved.

In the present embodiment, the average particle size of the carbon powder particles in the ink layer 20 is 0.5 to 5 micrometers. When the average particle size of the carbon powder particles in the ink layer 20 is 0.5 μm, the roughness of the ink layer 20 can be minimized, but the OD value of the ultrasonic fingerprint module 100 is not optimal. When the average particle size of the carbon powder particles in the ink layer 20 is 5 micrometers, the OD value of the ultrasonic fingerprint module 100 is excellent, but the roughness of the ink layer 20 is not optimal. In a preferred embodiment, the average particle size of the carbon powder particles in the ink layer 20 is 0.8 to 2 microns, and more preferably 1.0 micron. It can be understood that, when the average particle size of the carbon powder particles of the ink layer 20 is 0.8 μm, the roughness of the ink layer 20 can be similar to the minimum value, and the OD value of the ultrasonic fingerprint module 100 meets the performance requirement. When the average particle size of the carbon powder particles of the ink layer 20 is 2 micrometers, the OD value of the ultrasonic fingerprint module 100 is excellent, and the roughness of the ink layer 20 can be reduced. Furthermore, when the average particle size of the carbon powder particles in the ink layer 20 is 1 μm, the roughness of the ink layer 20 can be similar to the minimum value, and the OD value and the SNR value of the ultrasonic fingerprint module 100 can be excellent. Of course, the average particle diameter of the carbon powder particles in the ink layer 20 may also be approximately 1 micron, the roughness of the ink layer 20 may be similar to the minimum value, and the OD value and the SNR value of the ultrasonic fingerprint module 100 may also be excellent.

In this embodiment, the mass ratio of the carbon powder particles in the ink layer 20 is 2.5% to 15%. When the mass ratio of the carbon powder particles in the ink layer 20 is 2.5%, the roughness of the ink layer 20 can be minimized, but the OD value of the ultrasonic fingerprint module 100 is not optimal. When the mass ratio of the carbon powder particles in the ink layer 20 is 15%, the OD value of the ultrasonic fingerprint module 100 is higher, but the roughness of the ink layer 20 is not the minimum. In a preferred embodiment, the mass ratio of the carbon powder particles in the ink layer is 3.0% to 10%, and more preferably 5%. It can be understood that when the mass percentage of the carbon powder particles in the ink layer 20 is 3.0%, the roughness of the ink layer 20 can be similar to the minimum value, and the OD value of the ultrasonic fingerprint module 100 meets the performance requirement. When the mass percentage of the carbon powder particles in the ink layer 20 is 10%, the OD value of the ultrasonic fingerprint module 100 meets the requirement, and the roughness of the ink layer 20 can be reduced. Furthermore, when the mass ratio of the carbon powder particles in the ink layer 20 is 5%, the roughness of the ink layer 20 can be similar to the minimum value, and the OD value and the SNR value of the ultrasonic fingerprint module 100 can be excellent. Of course, the mass ratio of the carbon powder particles in the ink layer 20 may be approximately 5%, the roughness of the ink layer 20 may be approximately the minimum value, and the OD value and the SNR value of the ultrasonic fingerprint module 100 may also be excellent.

In order to further improve the roughness of said first surface 201 and the roughness of said second surface 202. The leveling agent is added in the preparation process of the ink layer 20, so that the surface roughness of the ink layer 20 is effectively reduced by utilizing the performances of surface defoaming, surface leveling control and better surface leveling property of the leveling agent. Namely, the ink layer 20 further contains a leveling agent, and the leveling agent is used for improving the leveling property of the finally formed ink layer in the manufacturing process. The mass ratio of the leveling agent in the ink layer 20 can be 0.2-1.5%. The leveling agent can be a fluorocarbon leveling agent, and the leveling agent can be fluorocarbon organic modified siloxane. The leveling agent may also be a polyether siloxane copolymer. As a preferred embodiment, the leveling agent may be a mixture of a fluorocarbon organo-modified siloxane and a polyether siloxane copolymer. The mass ratio of the fluorocarbon organic modified siloxane in the ink layer 20 can be 0.1-0.75%, and the mass ratio of the polyether siloxane copolymer in the ink layer 20 can be 0.1-0.75%. When the mass percentage of the fluorocarbon organic modified siloxane in the ink layer 20 is 5%, and the mass percentage of the polyether siloxane copolymer in the ink layer 20 is 5%, the polyether siloxane copolymer and the fluorocarbon siloxane have good complementarity, and the polyether siloxane copolymer has strong surface state control capability, good surface leveling property and certain defoaming effect. The leveling property of the ink layer 20 is good, the surface is smooth, the surface roughness can be controlled to be less than or equal to 0.5 Rz/mum, and the fingerprint identification efficiency of the ultrasonic fingerprint module 100 is improved. In the first embodiment, the average particle size of 50% of the particle size distribution of the carbon powder particles in the ink layer 20 is 5 μm. The mass percentage of the carbon powder in the ink layer 20 is 15%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.2%. The roughness tester is used to test the roughness of the ink layer 20 of the ultrasonic fingerprint module 100 in this embodiment, and the test result shows that the roughness of the ink layer 20 is 5.25Rz/μm. Adopt ultrasonic fingerprint function tester to carry out SNR value test to ultrasonic fingerprint module 100 in this embodiment, it is 9.45 to obtain the SNR value. An Optical Density (OD) value of the ultrasonic fingerprint module 100 in this embodiment is measured by an optical density meter, and the OD value is 6.1.

A second embodiment is provided, which is different from the first embodiment in that the mass ratio of the carbon powder in the ink layer 20 is reduced. The ink layer 20 is provided with carbon powder particles with 50% of particle size distribution and 5 μm of average particle size. The mass percentage of the carbon powder in the ink layer 20 is 10%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.2%. The roughness of the ink layer 20 was 5.04Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 9.52. The OD value of the ultrasonic fingerprint module 100 is 5.3. Therefore, the proportion of the carbon powder in the ink layer 20 is reduced, and the surface roughness of the ink layer 20 can be reduced.

It can be understood that, when the OD value of the ultrasonic fingerprint module 100 is greater than 4, the performance of the ultrasonic fingerprint module 100 is better.

A third embodiment is provided, which is different from the second embodiment in that the mass ratio of the carbon powder in the ink layer 20 is continuously reduced. The ink layer 20 is provided with carbon powder particles with 50% of particle size distribution and 5 μm of average particle size. The mass percentage of the carbon powder in the ink layer 20 is 5%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.2%. The roughness of the ink layer 20 was 4.76Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 9.65. The OD value of the ultrasonic fingerprint module 100 is 4.6. It can be seen that, although the mass ratio of the carbon powder in the ink layer 20 is reduced, the surface roughness of the ink layer 20 can be reduced, and the SNR value of the ultrasonic fingerprint module 100 is improved, the OD value of the ultrasonic fingerprint module 100 is also reduced.

A fourth embodiment is provided, which is different from the third embodiment in that the mass ratio of the carbon powder in the ink layer 20 is continuously reduced. The ink layer 20 is provided with carbon powder particles with 50% of particle size distribution and 5 μm of average particle size. The mass percentage of the carbon powder in the ink layer 20 is 2.5%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.2%. The roughness of the ink layer 20 was 4.42Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 9.7. The OD value of the ultrasonic fingerprint module 100 is 3.7. It can be seen that when the mass ratio of the carbon powder in the ink layer 20 is reduced to 2.5%, the OD value of the ultrasonic fingerprint module 100 is also reduced to 3.7, and the ultrasonic fingerprint module 100 does not meet the requirement of good performance.

A fifth embodiment is provided, which is different from the fourth embodiment in that the average particle size of the carbon powder in the ink layer 20 is reduced. The average particle size of 50% of the particle size distribution of the carbon powder particles of the ink layer 20 is 0.5 μm. The average particle size of 100% of the particle size distribution of the carbon powder particles of the ink layer 20 is less than 1 μm. The mass percentage of the carbon powder in the ink layer 20 is 5%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.2%. The roughness of the ink layer 20 was 0.82Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 10.25. The OD value of the ultrasonic fingerprint module 100 is 4.3. It can be seen that, when the average particle size of carbon powder in the ink layer 20 is reduced, the surface roughness of the ink layer 20 can be significantly reduced, and it can be ensured that the SNR value of the ultrasonic fingerprint module 100 is high, and the OD value of the ultrasonic fingerprint module 100 also meets the requirement of good performance, that is, the performance of the ultrasonic fingerprint module 100 is significantly improved.

A sixth embodiment is provided, which is different from the fifth embodiment in that the ratio of the leveling agent in the ink layer 20 is increased. The average particle size of 50% of the particle size distribution of the carbon powder particles of the ink layer 20 is 0.5 μm. The average particle size of 100% of the particle size distribution of the carbon powder particles of the ink layer 20 is less than 1 μm. The mass percentage of the carbon powder in the ink layer 20 is 5%. The leveling agent in the ink layer 20 is fluorocarbon organic modified siloxane. The mass ratio of the leveling agent in the ink layer 20 is 0.7%. The roughness of the ink layer 20 was 0.68Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 10.35. The OD value of the ultrasonic fingerprint module 100 is 4.4. As can be seen, when the mass ratio of the leveling agent in the ink layer 20 is increased, the surface roughness of the ink layer 20 is also decreased, and the SNR value of the ultrasonic fingerprint module 100 is increased. The OD value of the ultrasonic fingerprint module 100 is also increased.

A seventh embodiment is provided, which is different from the sixth embodiment in that the leveling agent in the ink layer 20 is a mixture of two different types of leveling agents. Specifically, the average particle size of 50% of the particle size distribution of the carbon powder of the ink layer 20 is 0.5 μm. The average particle size of 100% of the particle size distribution of the carbon powder particles of the ink layer 20 is less than 1 μm. The mass percentage of the carbon powder in the ink layer 20 is 5%. The leveling agent in the ink layer 20 is a mixed leveling agent of fluorocarbon organic modified siloxane and polyether siloxane copolymer. The mass ratio of the fluorocarbon organic modified siloxane in the ink layer 20 is 0.5%. The mass ratio of the polyether siloxane copolymer in the ink layer 20 is 0.5%. The roughness of the ink layer 20 was 0.41Rz/μm. The SNR value of the ultrasonic fingerprint module 100 is 10.55. The OD value of the ultrasonic fingerprint module 100 is 4.3. Therefore, the fluorocarbon organic modified siloxane belongs to a fluorocarbon leveling agent, has good substrate wettability and strong anti-shrinkage capacity, but the leveling agent is easy to stabilize bubbles and is difficult to foam. By adding various leveling agents into the forming material of the ink layer 20, the polyether siloxane copolymer and the fluorocarbon siloxane are found to have better complementarity, the polyether siloxane copolymer has strong surface state control capability and good surface leveling property, and simultaneously has a certain defoaming effect. After the polyether siloxane copolymer and the fluorocarbon siloxane are added into the forming material of the ink layer 20, the leveling property is good, the surface is smooth, and the surface roughness of the ink layer 20 can be controlled to be less than 0.5 Rz/mum.

It can be understood that, if the ink layer 20 has bubbles, the ultrasonic acoustic impedance of the bubbles is very small, so that the signal intensity is greatly attenuated or even not reduced when the ultrasonic signal penetrates through and reflects the bubbles, that is, the signal receiving intensity of the ultrasonic detection layer 10 at the position corresponding to the bubbles in the ink layer 20 is obviously different from that of other areas, which causes noise in the acquired fingerprint image, that is, the acquired fingerprint image is not clear. Therefore, by improving the bubbles in the ink layer 20, the definition of the fingerprint image acquired by the ultrasonic fingerprint module 100 can be improved.

In order to further reduce the number of bubbles in the ink layer 20. The defoaming agent is added into the forming material of the ink layer 20, so that the defoaming performance of the defoaming agent is utilized to reduce the quantity of bubbles in the ink layer 20. Namely, the ink layer 20 further contains a defoaming agent, and the defoaming agent is used for eliminating bubbles in the ink layer in the manufacturing process and eliminating the bubbles of the finally formed ink layer. The mass ratio of the defoaming agent in the ink layer 20 can be 1.0-3.0%. The defoamer can be modified dimethylsilane, and the defoamer can also be polyoxypropylene ethylene oxide glycerol ether. As a preferred embodiment, the defoamer may be a mixture of modified dimethylsilane and polyoxypropylene oxyethylene glyceryl ether. The mass ratio of the modified dimethylsilane may be 0.8 to 2.0%, and the mass ratio of the polyoxypropylene oxyethylene glycerin ether may be 0.2 to 1.0%. When the mass ratio of the fluorocarbon organic modified siloxane is 1.5% and the mass ratio of the polyether siloxane copolymer is 0.5% -1.0%, the ink layer 20 has no bubbles.

In the eighth embodiment, a defoaming agent is disposed in the forming material of the ink layer 20. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 15%. The defoaming agent in the forming material of the ink layer 20 is modified dimethylsilane. The mass ratio of the defoaming agent in the forming material of the ink layer 20 is 0.5%. The defoaming agent is added into the forming material of the ink layer 20, a large amount of bubbles exist after stirring, and after the forming material after stirring of the ink layer 20 is printed and formed on the fingerprint detection layer 10 through a screen printing process, a large amount of bubbles still exist in the ink layer 20. The OD value of the ultrasonic fingerprint module 100 is 6.1.

A ninth embodiment is provided, which is different from the eighth embodiment in that the mass ratio of the carbon powder in the ink layer 20 is reduced, and the mass ratio of the defoaming agent in the molding material of the ink layer 20 is increased. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 10%. The defoaming agent in the forming material of the ink layer 20 is modified dimethylsilane. The mass ratio of the defoaming agent in the forming material of the ink layer 20 is 0.8%. The defoaming agent is added into the forming material of the ink layer 20, a small amount of bubbles exist after stirring, and after the forming material after stirring of the ink layer 20 is printed and formed on the fingerprint detection layer 10 through a screen printing process, a small amount of bubbles still exist in the ink layer 20. The OD value of the ultrasonic fingerprint module 100 is 5.3. It can be seen that the higher the mass ratio of the carbon powder in the ink layer 20 is, the more easily the ink layer 20 generates bubbles during the preparation process. The bubble content in the ink layer 20 can be improved by reducing the mass ratio of the carbon powder in the ink layer 20 and increasing the mass ratio of the defoaming agent in the forming material of the ink layer 20.

In a tenth embodiment, unlike the ninth embodiment, the mass ratio of the toner in the ink layer 20 is continuously decreased, and the mass ratio of the defoaming agent in the ink layer 20 is continuously increased. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 5%. The defoaming agent in the ink layer 20 is modified dimethylsilane. The mass ratio of the defoaming agent in the ink layer 20 is 1.5%. The little amount of bubbles exist after the defoaming agent is added into the forming material of the ink layer 20 and the forming material after the ink layer 20 is stirred is printed and formed on the fingerprint detection layer 10 through the screen printing process, and the little amount of bubbles still exist in the ink layer 20. The OD value of the ultrasonic fingerprint module 100 is 4.6. Therefore, by reducing the carbon powder proportion in the ink layer 20 and increasing the mass proportion of the defoaming agent in the ink layer 20, the bubble content in the ink layer 20 can be obviously improved, but the OD value of the ultrasonic fingerprint module 100 can be obviously reduced, which easily causes the performance reduction of the ultrasonic fingerprint module 100.

In contrast to the tenth embodiment, the eleventh embodiment is provided in which the mass fraction of toner in the ink layer 20 is continuously decreased, and the mass fraction of the defoaming agent in the ink layer 20 is continuously increased. Specifically, the mass ratio of the carbon powder in the ink layer 20 is 2.5%. The defoaming agent in the ink layer 20 is modified dimethylsilane. The mass ratio of the defoaming agent in the ink layer 20 is 2.0%. The little amount of bubbles exist after the defoaming agent is added into the forming material of the ink layer 20 and the forming material after the ink layer 20 is stirred is printed and formed on the fingerprint detection layer 10 through the screen printing process, and the little amount of bubbles still exist in the ink layer 20. The OD value of the ultrasonic fingerprint module 100 is 3.7. When the mass ratio of the defoaming agent in the ink layer 20 is 2.0%, shrinkage cavities are obviously formed in the ink layer 20. It can be seen that the ink layer 20 cannot meet the use requirement when the mass ratio of the defoaming agent in the ink layer 20 is greater than 2.0%. The mass ratio of the carbon powder in the ink layer 20 is greater than or equal to 5%, and the mass ratio of the defoaming agent in the ink layer 20 is increased to approximately 1.5%, so that the OD value of the ultrasonic fingerprint module 100 can meet the minimum requirement, but the ink layer 20 cannot be ensured to be bubble-free.

A twelfth embodiment is provided, differing from the eleventh embodiment in that the defoaming agent in the ink layer 20 comprises two different types of defoaming agent. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 5%. The defoaming agent in the ink layer 20 is a mixture of modified dimethylsilane and polyoxypropylene ethylene oxide glyceryl ether. The mass percentage of the modified dimethylsilane in the ink layer 20 is 1.5%. The mass ratio of the polyoxypropylene ethylene oxide glycerol ether in the ink layer 20 is 0.2%. The defoaming agent is added into the forming material of the ink layer 20, no bubbles are generated after stirring, and the forming material after stirring the ink layer 20 is printed and formed on the fingerprint detection layer 10 through a screen printing process, so that a very small amount of bubbles still exist in the ink layer 20. The OD value of the ultrasonic fingerprint module 100 is 4.5. It can be seen that, the defoaming agent in the forming material of the ink layer 20 contains modified dimethylsilane and polyoxypropylene ethylene oxide glyceryl ether, so that the bubble content of the ink layer 20 in the preparation process is obviously improved, the OD value of the ultrasonic fingerprint module 100 also meets the performance requirement, but a very small amount of bubbles still exist in the finally formed ink layer 20.

A thirteenth embodiment is provided, which is different from the twelfth embodiment in that the ratio of the mass of the polyoxypropylene ethylene oxide glycerin ether in the ink layer 20 is increased. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 5%. The defoaming agent in the ink layer 20 is a mixture of modified dimethylsilane and polyoxypropylene ethylene oxide glyceryl ether. The mass percentage of the modified dimethylsilane in the ink layer 20 is 1.5%. The mass ratio of the polyoxypropylene ethylene oxide glycerol ether in the ink layer 20 is 0.5%. The defoaming agent is added into the forming material of the ink layer 20, no bubble is generated after stirring, and the forming material after stirring of the ink layer 20 is printed and formed on the fingerprint detection layer 10 through a screen printing process, so that the ink layer 20 has no bubble. The OD value of the ultrasonic fingerprint module 100 is 4.6. It can be seen that, the defoaming agent in the forming material of the ink layer 20 contains modified dimethylsilane and polyoxypropylene ethylene oxide glyceryl ether, and after the mass ratio of the polyoxypropylene ethylene oxide glyceryl ether is increased, the ink layer 20 has no bubbles in the preparation process, the finally formed ink layer 20 has no bubbles, and the OD value of the ultrasonic fingerprint module 100 also meets the performance requirement, so that the performance of the ultrasonic fingerprint module 100 is obviously improved.

A fourteenth embodiment is provided, which is different from the thirteenth embodiment in that the mass ratio of the polyoxypropylene ethylene oxide glycerin ether in the molding material of the ink layer 20 is continuously increased. Specifically, the mass percentage of the carbon powder in the ink layer 20 is 5%. The defoaming agent in the ink layer 20 is a mixture of modified dimethylsilane and polyoxypropylene ethylene oxide glyceryl ether. The mass percentage of the modified dimethylsilane in the ink layer 20 is 1.5%. The mass ratio of the polyoxypropylene ethylene oxide glycerol ether in the ink layer 20 is 1.0%. The defoaming agent is added into the forming material of the ink layer 20, no bubble is generated after stirring, and the forming material after stirring of the ink layer 20 is printed and formed on the fingerprint detection layer 10 through a screen printing process, so that the ink layer 20 has no bubble. The OD value of the ultrasonic fingerprint module 100 is 4.6.

Further, referring to fig. 2, the ultrasonic detection layer 10 includes a substrate layer 13, a plurality of pixel electrodes 14, a piezoelectric layer 15 and a conductive electrode 16, the plurality of pixel electrodes 14 are arranged in the substrate layer 13 in an array, the piezoelectric layer 15 covers the plurality of pixel electrodes 14, the conductive electrode 16 is laminated on a surface of the piezoelectric layer 15 away from the plurality of pixel electrodes 14, and the ink layer 20 is formed by printing on a surface of the conductive electrode 16 away from the piezoelectric layer 15.

In this embodiment, the base material layer 13 may be made of glass or a polyimide film material. Substrate layer 13's cost is lower, the light transmissivity is better, and is convenient ultrasonic wave fingerprint module 100 is integrated in electronic equipment's display screen. When ultrasonic fingerprint module 100 is integrated in the display screen, the ultrasonic fingerprint module 100 that has better light transmissivity can not shelter from display screen 90's display image, and ultrasonic fingerprint module 100 integrated in display screen 90 simultaneously can keep display screen 90's whole colour unanimous and improve display screen 90's appearance quality.

In this embodiment, the pixel electrodes 14 may be formed on the substrate layer 13 by a TFT printing process and distributed in an array. The pixel electrode 14 is made of any one of Indium Tin Oxide (ITO), nano silver wire (silver wire), metal mesh (metal mesh), carbon nanotube, and Graphene (Graphene), and the pixel electrode 14 made of the above materials has good toughness and light transmittance. So that the ultrasonic fingerprint module 100 made of the pixel electrode 14 has better toughness and light transmittance. The light transmittance of the pixel electrode 14 is greater than 90%, so that the ultrasonic fingerprint module 100 made of the pixel electrode 14 has better light transmittance. The pixel electrodes 14 can be used for receiving electric signals, each pixel electrode 14 can determine a position of the ultrasonic fingerprint module 100 according to the received electric signals, and the density of the pixel electrodes 14 on the substrate layer 13 is positively correlated with the fingerprint collection precision of the ultrasonic fingerprint module 100. The density of the array arrangement of the pixel electrodes 14 ensures the accuracy of the fingerprint image of the object to be detected by the ultrasonic sensor.

In the present embodiment, the ultrasonic wave receiving surface 11 is provided on the piezoelectric layer 15 on the side facing the base material layer 13. The piezoelectric layer 15 is laminated on the base material layer 13 and covers the plurality of pixel electrodes 14. The piezoelectric layer 15 is a sheet structure made of piezoelectric material. The shape of the piezoelectric layer 15 matches the shape of the substrate layer 13. The material of the piezoelectric layer 15 is polyvinylidene fluoride (PVDF). Because polyvinylidene fluoride has better toughness and light transmissivity, make piezoelectric layer 15 has better pliability and light transmissivity, has guaranteed ultrasonic fingerprint module 100's pliability and light transmissivity. The piezoelectric layer 15 is capable of generating ultrasonic waves under the action of a high-frequency voltage (for example, a voltage with a frequency greater than 20 KHZ). After the piezoelectric layer 15 receives the ultrasonic wave reflected by the object to be detected, the piezoelectric layer 15 generates an electric signal (or a piezoelectric signal) under the action of the ultrasonic wave, and the object to be detected can be a finger, a test template and the like.

In this embodiment, the conductive electrode 16 is an integral layered structure made of a conductive material. The shape of the conductive electrode 16 matches the shape of the piezoelectric layer 15. The material of the conductive electrode 16 may be silver material. The conductive electrode 16 may be formed after silver paste is cured. The light transmittance of the conductive electrode 16 is greater than 90%. After the conductive electrode 16 and the pixel electrode 14 are energized with a high frequency voltage, the high frequency voltage can be applied to the piezoelectric layer 15, so that the piezoelectric layer 15 generates an ultrasonic signal to detect a user fingerprint by using the ultrasonic signal. The conductive electrode 16 and the pixel electrode 14 can also receive an electrical signal generated by the piezoelectric layer 15. The bottom surface 12 of the detection layer is disposed on a surface of the conductive electrode 16 away from the piezoelectric layer 15. The ink layer 20 covers the conductive electrode 16, and can prevent the conductive electrode 16 from being oxidized. The ink layer 20 may also mask cosmetic defects on the conductive electrode 16.

In this embodiment, the thickness of the conductive electrode 16 is 10 to 30 micrometers, the thickness of the piezoelectric layer 15 is 5 to 15 micrometers, and the thickness of the base material layer 13 is 80 to 100 micrometers. The thickness of the ink layer 20 is 7 to 30 micrometers. Utilize the thin performance of ultrasonic fingerprint module 100 is convenient ultrasonic fingerprint module 100 is integrated in electronic equipment's display screen.

It is understood that the ink layer 20 is printed on the fingerprint detection layer 10, that is, the ink layer 20 is printed on the conductive electrode 16. The surface roughness of the conductive electrode 16 has an effect on the roughness of the first surface 201 of the ink layer 20.

Through testing, the ink layer 20 with different thicknesses is formed on the glass substrate with smaller surface roughness, and the surface roughness of the formed ink layer 20 is measured, so that the influence of the thickness of the ink layer 20 on the surface roughness of the formed ink layer 20 is not great. For example, ink layers 20 having film thicknesses of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, and 30 μm are formed on a glass substrate, and the surface roughness of the ink layers 20 after forming is 0.375Rz/μm, 0.355Rz/μm, 0.335Rz/μm, 0.315Rz/μm, 0.316Rz/μm, and 0.322Rz/μm, respectively.

Through testing, a plurality of ink layers 20 with different thicknesses are respectively formed on a plurality of fingerprint detection layers 10, a plurality of ultrasonic fingerprint modules 100 are finally obtained, and the surface roughness of the ink layer 20 of the ultrasonic fingerprint module 100 is measured, so that the thicker the ink layer 20 is, the smaller the surface roughness of the ink layer 20 is, and when the thickness of the ink layer 20 is approximately 25 μm, the surface roughness of the ink layer 20 is not reduced along with the reduction of the thickness of the ink layer 20, namely, the surface roughness of the ink layer 20 tends to be stable and does not reduce.

In one embodiment, six of the fingerprint detection layers 10 are arranged with a surface roughness towards the ink layer 20 of between 3.5Rz/μm and 4.5Rz/μm. The thickness of the substrate layer 13 in the six fingerprint detection layers 10 is 90 μm, the thickness of the piezoelectric layer 15 is 9 μm, and the thickness of the conductive electrode 16 is 15-18 μm. Six ink layers 20 with the film thicknesses of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm and 30 μm are respectively formed on the six fingerprint detection layers 10, and the surface roughness of the six formed ink layers 20 is detected to be 1.712Rz/μm, 1.06Rz/μm, 0.72Rz/μm, 0.527Rz/μm, 0.309Rz/μm and 0.324Rz/μm respectively. Obviously, when the thickness of the ink layer 20 is 20 μm to 30 μm, the surface roughness of the ink layer 20 of the ultrasonic fingerprint module 100 is small, and the performance of the ultrasonic fingerprint module 100 is excellent.

In another embodiment, as shown in fig. 3, the ink layer 20 is provided with a plurality of ink layers 22, and the plurality of ink layers 22 are sequentially stacked.

In this embodiment, the ink layer 20 is formed by a plurality of printing steps, and each of the ink layers 22 is formed in each of the printing steps. After each of the ink layers 22 is cured, another ink layer 22 is formed. The thickness of each of the ink seed layers 22 may be set the same. By precisely controlling the surface roughness of each ink layer 22, the surface roughness of the finally formed ink layer 20 can be more excellent, so as to ensure that the ultrasonic fingerprint module 100 has excellent performance.

Referring to fig. 4, the present application provides a method for manufacturing an ultrasonic fingerprint module, including the steps of:

101: an ultrasonic detection layer 10 is provided.

In the present embodiment, first, the base layer 13 is molded. The substrate layer 13 may be made of glass or a polyimide film material. The substrate layer 13 has good mechanical strength, so that other structural components can be conveniently formed on the substrate layer 13, and the ultrasonic fingerprint film 100 can be conveniently and stably connected with a shell of an electronic device or the back of a display screen of the electronic device. The length and width of the substrate layer 13 can be designed according to the required length and width of the ultrasonic fingerprint module 100, so that the length and width of the ultrasonic fingerprint module 100 can meet the specification requirement.

Then, a pixel electrode layer is formed on the base material layer 13. The pixel electrode layer is constituted by a plurality of pixel electrodes 14. The length and width of the pixel electrode layer are substantially the same as those of the base material layer 13. The plurality of pixel electrodes 14 of the pixel electrode layer may be formed on the substrate layer 13 through a TFT printing process. The pixel electrode 14 is made of any one of Indium Tin Oxide (ITO), nano silver wire (silver wire), metal mesh (metal mesh), carbon nanotube, and Graphene (Graphene), and the pixel electrode 14 made of the above materials has good toughness and light transmittance.

Then, a piezoelectric layer 15 is formed on the pixel electrode layer. The piezoelectric layer 15 has a length and a width substantially equal to those of the pixel electrode layer. The piezoelectric layer 15 covers the plurality of pixel electrodes 14. The piezoelectric layer 15 is a sheet structure made of piezoelectric material. The shape of the piezoelectric layer 15 matches the shape of the substrate layer 13. The material of the piezoelectric layer 15 is polyvinylidene fluoride (PVDF). Because polyvinylidene fluoride has better toughness and light transmissivity, make piezoelectric layer 15 has better pliability and light transmissivity, has guaranteed ultrasonic fingerprint module 100's pliability and light transmissivity.

Then, a conductive electrode 16 is formed on the piezoelectric layer 15. The length and width of the conductive electrode 16 are the same as those of the pixel electrode layer, so that the conductive electrode 16 is matched with the pixel electrode layer. The conductive electrode 16 may be formed on the piezoelectric layer 15 by a screen printing process. The conductive electrode 16 is an integral layered structure made of a conductive material. The shape of the conductive electrode 16 matches the shape of the piezoelectric layer 15. The material of the conductive electrode 16 may be silver material. The conductive electrode 16 may be formed after silver paste is cured. Two or more layers of the conductive electrodes 16 may be formed on the piezoelectric layer 15, so that the surface roughness of the outermost layer of the conductive electrodes 16 away from the piezoelectric layer 15 is smaller, i.e. the bottom surface of the detection layer of the ultrasonic detection layer 10 is smoother.

102: a liquid ink material containing a resin material and carbon powder particles is provided.

In the present embodiment, the resin material may be any one of an acrylic resin, a polyester resin, an isocyanate resin, a phenoxy resin, and an epoxy resin, or a combination of a plurality of these resin materials. As a better embodiment, the liquid ink material is formed by mixing and stirring epoxy resin and carbon powder particles.

Furthermore, the liquid ink material also contains a defoaming agent and a leveling agent. Namely, the epoxy resin, the carbon powder particles, the defoaming agent and the flatting agent are mixed and stirred to form the liquid ink material.

The liquid ink material containing the defoaming agent can effectively reduce the number of bubbles in the ink layer 20, and improve the reflection efficiency of the ink layer 20 to ultrasonic waves. The defoaming agent can be modified dimethylsilane or polyoxypropylene ethylene oxide glycerol ether, or a mixed defoaming agent of the modified dimethylsilane and the polyoxypropylene ethylene oxide glycerol ether. The mass ratio of the defoaming agent in the ink layer 20 is 1.0-3.0%. In a preferred embodiment, the mass ratio of the defoaming agent is 1.5-2.5%. When the mass of defoaming agent accounts for than in 1.5% in the printing ink layer 20 for liquid printing ink material can have less bubble after the stirring, and make the printing ink layer 20 that forms after the liquid printing ink material solidifies also have less bubble, ultrasonic fingerprint module 100 satisfies the fingerprint identification demand. When the quality of defoaming agent accounts for than being 2.5% in the printing ink layer 20 and can effectively eliminate the bubble in the liquid printing ink material after the stirring to can make the printing ink layer 20 that forms after the liquid printing ink material solidification also not contain the bubble, the ultrasonic fingerprint module 100 that is equipped with this printing ink layer 20 is excellent in performance, and fingerprint identification is efficient.

The leveling agent is contained in the liquid ink material, so that the surface roughness of the ink layer 20 can be effectively reduced, and the reflection efficiency of the ink layer 20 to ultrasonic waves is improved. The leveling agent can be fluorocarbon organic modified siloxane or polyether siloxane copolymer, or a mixed leveling agent of fluorocarbon organic modified siloxane and polyether siloxane copolymer. The mass percentage of the leveling agent in the ink layer 20 is 0.2-1.5%. In a preferred embodiment, the mass ratio of the leveling agent in the ink layer 20 is 0.5% to 1.0%. When the mass ratio of the leveling agent in the ink layer 20 is 0.5%, the surface of the ink layer 20 formed after the liquid ink material is cured is smooth, and the surface roughness of the ink layer 20 can be controlled to be 0.6Rz/μm. When the mass percentage of the leveling agent is 1.0%, the surface roughness of the ink layer 20 formed after the liquid ink material is cured can be controlled to be 0.4 Rz/mum, so that the ultrasonic identification efficiency of the ultrasonic fingerprint module 100 is effectively improved.

103: and the liquid ink material is laid on the bottom surface of the detection layer of the ultrasonic detection layer 10, an ink layer 20 is formed after the liquid ink material is solidified, and the ink layer 20 covers the ultrasonic receiving surface of the ultrasonic detection layer 10.

In this embodiment, the surface of the outermost conductive electrode 16, which is away from the piezoelectric layer 15, forms the detection layer bottom surface of the ultrasonic detection layer 10. The liquid ink material may be formed on the conductive electrode 16 by vacuum evaporation, screen printing, spraying, or sputtering.

In another embodiment, the length and width of the substrate layer 13 may be processed according to a design size at least n times the length and width of the ultrasonic fingerprint module 100, so that after the pixel electrode layer 14, the piezoelectric layer 15, the conductive electrode 16 and the ink layer 20 with a large area are sequentially formed on the substrate layer 13, a plurality of ultrasonic fingerprint modules 100 may be obtained in batch by cutting. The pixel electrode layer 15, the piezoelectric layer 15, the conductive electrode 16 and the ink layer 20 can be processed and molded according to a plurality of preset ultrasonic fingerprint module 100 array arrangement areas, so that the manufacturing cost for obtaining a plurality of ultrasonic fingerprint modules 100 in batches is reduced.

Referring to fig. 5, the present application further provides a display screen assembly 200, where the display screen assembly 200 includes a display screen 210 and the ultrasonic fingerprint module 100. The display screen 210 has an outer surface 211 facing a user, the ultrasonic fingerprint module 100 is fixed in the screen of the display screen 210 or under the screen, and the ink layer 20 is far away from the outer surface 211 relative to the ultrasonic detection layer 10.

Referring to fig. 6, in one embodiment, the ink layer 20 of the ultrasonic fingerprint module 100 is not transparent to visible light. The ultrasonic fingerprint module 100 is fixed under the screen of the display screen 210, and the ink layer 20 blocks the display light of the display screen 210 from exiting from the surface far away from the outer surface 211.

Specifically, the display screen 210 is provided with an organic electroluminescent layer 212, and the ultrasonic detection layer 10 is laminated on one surface of the organic electroluminescent layer 212 far from the outer surface 211. The display screen 210 is provided with a glass cover plate 213. The outer surface 211 is disposed on the glass cover plate 213. The organic electroluminescent layer 212 is attached to the glass cover plate 213. The substrate layer 13 of the ultrasonic detection layer 10 is bonded to the organic electroluminescent layer 212. The substrate layer 13 may constitute a base layer of the organic electroluminescent layer 212. The substrate layer 13 may be bonded to the organic electroluminescent layer 212 through a glue layer. The display screen 210 is an OLED (Organic Light-Emitting Diode) display screen 210. By utilizing the light-tight property of the ink layer 20 of the ultrasonic fingerprint module 100, the ink layer 20 can form a back plate of the display screen 210, so that the display screen 210 can display images conveniently. The display screen 210 may be a flexible display screen. The ultrasonic fingerprint module 100 can be bent and deformed along with the display screen 210.

It can be understood that, by setting the distance from the side of the fingerprint detection layer 10 attached to the ink layer 20 to the outer surface 211 and setting the ultrasonic detection layer 10 to emit ultrasonic frequency, the piezoelectric layer 15 of the ultrasonic detection layer 10 emits a first ultrasonic signal 01 toward the outer surface 211 and emits a second ultrasonic signal 02 toward the ink layer 20. The second ultrasonic signal 02 is reflected by the interface between the ink layer 20 and the air to form a third ultrasonic signal 03. The third ultrasonic signal 03 is also emitted towards said outer surface 211. The third ultrasonic signal 03 and the first ultrasonic signal 01 may form resonance and are emitted toward the outer surface 211 together to enhance fingerprint recognition efficiency.

Through testing, six display screen assemblies 200 are provided, the thicknesses of the ink layers 20 in the six display screen assemblies 200 are different from each other, and the SNR values of the ultrasonic fingerprint modules 100 in the six display screen assemblies 200 and the acquired fingerprint image resolution (LPMM) values are compared. For example, the thicknesses of the ink layers 20 in the six display screen assemblies 200 are respectively 5 μm, 10 μm, 15 μm, 20 μm, 25 μm and 30 μm, the SNR values of the ultrasonic fingerprint modules 100 in the six display screen assemblies 200 are respectively 4.571, 4.9, 5.308, 5.859, 6.105 and 5.72 after testing, and the fingerprint image resolution (LPMM) values obtained by the ultrasonic fingerprint modules 100 in the six display screen assemblies 200 are respectively 3.23, 3.32, 3.421, 3.594, 3.593 and 3.6. It can be seen that, when the thickness of the ink layer 20 is 25 μm, the performance of the ultrasonic fingerprint module 100 of the display screen assembly 200 is excellent. That is, as a preferred embodiment, the thickness of the ink layer 20 of the ultrasonic fingerprint module 100 may be set to be 20 μm to 30 μm.

Referring to fig. 7 and fig. 8, in another embodiment, substantially the same as the embodiment shown in fig. 6, except that the display screen 210 is provided with a liquid crystal panel 214 and a backlight module 215, the backlight module 215 includes a backlight light guide plate 216 attached to the liquid crystal panel 214 and a backlight source 217 fixed to a side of the backlight light guide plate 216, and the ultrasonic detection layer 10 is attached to a surface of the backlight light guide plate 216 away from the liquid crystal panel 214. The liquid crystal panel 214 is attached to the glass cover plate 213. The substrate layer 13 is attached to the backlight light guide plate 216. The substrate layer 13 may constitute a base layer of the backlight light guide plate 216. Due to the non-light-permeability of the ink layer 20, the ink layer 20 can form a back plate of the backlight module 215, so that the liquid crystal panel 214 obtains light rays of the backlight module 215, and further, images are displayed. In order to increase the structural stability of the backlight module 215, the backlight module 215 further includes a package substrate 218, the package substrate 218 encapsulates the backlight source 217 and the backlight light guide plate 216, and the ultrasonic fingerprint module 100 is fixed between the backlight light guide plate 216 and the package substrate 218. The package substrate 218 protects the ultrasonic fingerprint module 100, and the package substrate 218 further packages the backlight source 217 to prevent the backlight source 217 from leaking light. The package bottom plate 218 may be a bendable sheet metal piece. There is an assembly gap between the package substrate 218 and the ultrasonic fingerprint module 100 to increase the ultrasonic blocking rate of the ink layer 20, and ensure the effectiveness of the ultrasonic fingerprint module 100 in recognizing fingerprints.

Referring to fig. 9, in another embodiment, substantially the same as the embodiment shown in fig. 6, the ultrasonic fingerprint module 100 can be embedded in the display screen 210, and the ultrasonic fingerprint module 100 is located in a non-display area of the display screen 210. Specifically, the glass cover plate 213 has a non-light-transmitting area 2131. The opaque region 2131 of the glass cover plate 213 is formed of an ink layer attached to the glass. The opaque area 2131 of the glass cover plate 213 covers the ultrasonic fingerprint module 100, so as to ensure the appearance performance of the display screen 210 assembly 200. Utilize ultrasonic wave fingerprint module 100 set up in the non-display area of display screen 210 subassembly 200 avoids ultrasonic wave fingerprint module 100's printing ink layer 20 blocks and shows light, in order to guarantee the display effect of the display area of display screen 210 subassembly 200. There is the clearance between the printing ink layer 20 of ultrasonic wave fingerprint module 100 and other layer structure of display screen 210 subassembly 200 to guarantee printing ink layer 20 blocks efficiency to the ultrasonic wave, guarantees the fingerprint identification validity of ultrasonic wave fingerprint module 100.

Referring to fig. 10, in another embodiment, substantially the same as the embodiment shown in fig. 7, except that the display panel 210 is provided with a substrate 2101 attached to the organic electroluminescent layer 212, the ultrasonic detection layer 10 includes a plurality of pixel electrodes 14, a piezoelectric layer 15 and a conductive electrode 16, the plurality of pixel electrodes 14 are arranged in an array on a surface of the substrate 2101 away from the glass cover 213, the piezoelectric layer 15 covers the plurality of pixel electrodes 14, the conductive electrode 16 is laminated on a surface of the piezoelectric layer 15 away from the plurality of pixel electrodes 14, and the ink layer 20 is formed by printing on a surface of the conductive electrode 16 away from the piezoelectric layer 15. That is, the ultrasonic fingerprint module 100 is attached to the substrate 2101 of the display screen 210. Of course, in other embodiments, the display screen 210 is provided with the substrate 2101 of the liquid crystal panel 214, and the plurality of pixel electrodes 14 of the ultrasonic fingerprint module 100 may be formed on the substrate 2101 of the liquid crystal panel 214.

Referring to fig. 11, the present application further provides an electronic device 300, where the electronic device 300 includes the display screen assembly 200, and the electronic device 300 further includes a rear cover 310 and a main board 320. The display screen 210 is covered with the rear cover 310. The main board 320 is fixed between the rear cover 310 and the display screen 210, and the main board 320 is electrically connected to the display screen 210 and the ultrasonic fingerprint module 100. The main board 320 can receive the electrical signal of the ultrasonic fingerprint module 100 to identify a fingerprint image of a user. It can be understood that ultrasonic fingerprint module 100 can receive the fingerprint detected signal through user's fingerprint detection, the fingerprint detected signal through user's fingerprint detection can be by the initial detected signal conduction of ultrasonic fingerprint module 100 transmission is to user's fingerprint, also can be by the initial detected signal conduction of outside ultrasonic signal source transmission to user's fingerprint. The electronic device 300 may be a mobile phone, a tablet computer, a notebook computer, a media player, or a financial terminal device such as an Automated Teller Machine (ATM). Electronic equipment 300 is through inciting somebody to action ultrasonic wave fingerprint module 100 set up in the display screen 210, make electronic equipment 300 can satisfy diversified fingerprint identification requirement, improves fingerprint identification efficiency.

It is to be understood that any specific numerical value having a protective meaning in this embodiment is not limited to the specific numerical values provided above, and other numerical values similar to the specific numerical values provided in this embodiment are also within the protective scope of the embodiments of the present application.

The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.

Claims

1. The utility model provides an ultrasonic fingerprint module, its characterized in that, ultrasonic fingerprint module includes ultrasonic detection layer and printing ink layer, the ultrasonic detection layer has the ultrasonic wave and receives the face, the printing ink layer set up in the ultrasonic detection layer is kept away from the one side that the ultrasonic wave received the face, the printing ink layer is used for the follow the ultrasonic wave that the ultrasonic detection layer jetted out reflects.

2. The ultrasonic fingerprint module of claim 1, wherein the ink layer comprises a resin material and carbon powder particles.

3. The ultrasonic fingerprint module of claim 2, wherein the carbon powder particles have an average particle size of 0.5 to 5 microns.

4. The ultrasonic fingerprint module of claim 3, wherein the carbon powder particles have an average particle size of 0.8 to 2 microns.

5. The ultrasonic fingerprint module according to claim 2, wherein the mass ratio of the carbon powder particles in the ink layer is 2.5-15%.

6. The ultrasonic fingerprint module of claim 5, wherein the mass ratio of the carbon powder particles in the ink layer is 3.0-10%.

7. The ultrasonic fingerprint module of claim 2, wherein the resin material is epoxy.

8. The ultrasonic fingerprint module of claim 7, wherein the resin material is an epoxy resin having a CAS number of 38891-59-7.

9. The ultrasonic fingerprint module of claim 2, wherein the ink layer further comprises a leveling agent, and the leveling agent is used to improve the surface leveling property during the ink layer manufacturing process and the surface leveling property of the finally formed ink layer.

10. The ultrasonic fingerprint module of claim 2, wherein the ink layer further comprises a defoaming agent, and the defoaming agent is used for eliminating bubbles in the ink layer during the manufacturing process and eliminating bubbles in the finally formed ink layer.

11. The ultrasonic fingerprint module of any one of claims 1 to 10, wherein the thickness of the ink layer is 5 to 30 microns.

12. The ultrasonic fingerprint module of claim 11, wherein the ink layer has a thickness of 20 to 30 microns.

13. The ultrasonic fingerprint module of claim 12, wherein the ink layer has a thickness of 25 microns.

14. The ultrasonic fingerprint module according to any one of claims 1 to 10, wherein the ultrasonic detection layer comprises a substrate layer, a pixel electrode layer, a piezoelectric layer and a conductive electrode, which are sequentially stacked, and the ink layer is disposed on a surface of the conductive electrode, which is far away from the piezoelectric layer.

15. The utility model provides a display screen subassembly, its characterized in that, the display screen subassembly includes display screen and any one of claim 1 ~ 14 ultrasonic fingerprint module, the display screen has the surface towards the user, ultrasonic fingerprint module is fixed in the screen of display screen or under the screen, the printing ink layer is relative the ultrasonic detection layer is kept away from the surface.

16. An electronic device, characterized in that the electronic device comprises the display screen assembly of claim 15.