Fingerprint recognition device

Abstract

The embodiment of the present application discloses a fingerprint recognition device, comprising: a first substrate, a piezoelectric layer, an electrode layer, a backing, a packaging layer and an adhesive structure, wherein at least one adhesive layer is arranged in a sealed cavity formed by the packaging layer, the backing and the electrode layer, the adhesive layer comprises a plurality of adhesive units, and there is a gap between adjacent adhesive units, so that the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the backing side is reflected back and forth at the interface between the adhesive unit and the gap when it is transmitted to the inside of each adhesive unit in the at least one adhesive layer, so that the adhesive unit has a strong absorption effect on the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the backing side, thereby significantly reducing the influence of the reflected ultrasonic wave signal amount formed during the transmission process of the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the backing side on the fingerprint recognition accuracy of the fingerprint recognition device, thereby improving the fingerprint recognition accuracy.

Description

Technical Field

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

[0002] With the development of electronic technology, more and more electronic devices have integrated fingerprint recognition functions to improve the security of electronic devices. Current fingerprint recognition devices include optical fingerprint recognition devices and ultrasonic fingerprint recognition devices. Among them, ultrasonic fingerprint recognition devices do not require the light source of the display, and ultrasonic waves have strong penetration ability, are not affected by light, have high anti-stain ability, can recognize wet and dirty fingers, and can recognize duplicate fingerprints. They are highly secure and have gradually become the mainstream trend of fingerprint recognition devices in electronic devices. Therefore, how to further improve the fingerprint recognition accuracy of ultrasonic fingerprint recognition devices has become a research hotspot for technicians in this field. Summary of the invention

[0003] In order to solve the above technical problems, the embodiments of the present application provide a fingerprint recognition device to improve the fingerprint recognition accuracy of an ultrasonic fingerprint recognition device.

[0004] To solve the above problems, the present application provides the following technical solutions:

[0005] A fingerprint recognition device, comprising:

[0006] A first substrate, wherein the first substrate has a first control circuit;

[0007] a piezoelectric layer, the piezoelectric layer being located on a first side surface of the first substrate;

[0008] an electrode layer, the electrode layer covering the piezoelectric layer and electrically connecting the first control circuit and the piezoelectric layer;

[0009] A backing, the backing being located on a side of the electrode layer away from the piezoelectric layer;

[0010] An encapsulation layer, wherein the encapsulation layer covers the side wall of the backing, and the encapsulation layer, the backing and the electrode layer form a sealed cavity;

[0011] The bonding structure is located in the sealing cavity, the bonding structure includes at least one bonding layer, the bonding layer includes a plurality of bonding units, and there are gaps between adjacent bonding units.

[0012] Compared with the prior art, the above technical solution has the following advantages:

[0013] According to the technical solution provided in the embodiment of the present application, at least one adhesive layer is arranged in the sealed cavity formed by the packaging layer, the backing and the electrode layer, and the adhesive layer includes a plurality of adhesive units, and there is a gap between adjacent adhesive units, so that the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing is reflected back and forth at the interface between the adhesive unit and the gap when it is transmitted to the inside of each adhesive unit in the at least one adhesive layer, so that the adhesive unit has a strong absorption effect on the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing, thereby greatly reducing the amount of reflected ultrasonic wave signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic wave signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing during the transmission process on the fingerprint recognition accuracy of the fingerprint recognition device, thereby improving the fingerprint recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a schematic diagram of the structure of a current fingerprint recognition device;

[0016] Figure 2 A schematic diagram of the structure of a fingerprint recognition device provided by an embodiment of the present application;

[0017] Figure 3 A schematic diagram of the structure of a fingerprint recognition device provided by another embodiment of the present application;

[0018] Figure 4 A top view of a plurality of bonding units in a bonding layer in a fingerprint recognition device provided by an embodiment of the present application;

[0019] Figure 5 A schematic diagram of the structure of a fingerprint recognition device provided in yet another embodiment of the present application;

[0020] Figure 6 A schematic diagram of the structure of a fingerprint recognition device provided in yet another embodiment of the present application;

[0021] Figure 7 A top view of a plurality of bonding units in a bonding structure in a fingerprint recognition device provided by an embodiment of the present application;

[0022] Figure 8A top view of a plurality of bonding units in a bonding structure in a fingerprint recognition device provided by another embodiment of the present application;

[0023] Fig. 9 A schematic diagram of the structure of a fingerprint recognition device provided in yet another embodiment of the present application;

[0024] Fig.10 A schematic diagram of the structure of a fingerprint recognition device provided in yet another embodiment of the present application;

[0025] Fig.11 A top view of a bonding structure in a fingerprint recognition device provided by another embodiment of the present application;

[0026] Fig.12 A schematic diagram of the structure of a fingerprint recognition device provided in yet another embodiment of the present application;

[0027] Fig.13 A schematic diagram of the relative positions of the electrode layer and the packaging layer in a fingerprint recognition device provided by an embodiment of the present application;

[0028] Fig.14 A top view of a fingerprint recognition device provided by an embodiment of the present application;

[0029] Fig.15 This is a schematic structural diagram of a fingerprint recognition device provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0032] As described in the background technology section, how to further improve the fingerprint recognition accuracy of ultrasonic fingerprint recognition devices has become a research hotspot for those skilled in the art.

[0033] like Figure 1As shown, the existing ultrasonic fingerprint recognition device includes: a control substrate 01, a piezoelectric layer (PVDF) 02 located on the surface of the control substrate 01, a silver paste electrode 03 located on the side of the piezoelectric layer 02 away from the control substrate 01 and covering the piezoelectric layer 02, and a backing 04 located on the side of the silver paste electrode 03 away from the piezoelectric layer 02. During operation, the control substrate drives the piezoelectric layer to generate ultrasonic waves, which are transmitted to one side of the control substrate and reflected on the surface of the fingerprint recognition device to form a reflected wave, which is used to form a fingerprint image for fingerprint recognition.

[0034] However, the ultrasonic fingerprint recognition device continues to work as Figure 1 As shown, the ultrasonic wave generated by the control substrate 01 driving the piezoelectric layer 02 will not only be transmitted to the control substrate 01 side, but also to the backing 04 side. The thickness of the silver paste electrode 03 is relatively large, which causes the piezoelectric layer 02 to be transmitted to the control substrate 01 side. The first reflected wave formed by the reflection of the finger on the upper surface of the fingerprint recognition device will interfere and superimpose with the second reflected wave formed by the piezoelectric layer transmitting to the backing side, resulting in a large difference between the waveform of the reflected wave used to form the fingerprint image and the waveform of the first reflected wave, thereby affecting the fingerprint recognition accuracy.

[0035] In view of this, an embodiment of the present application provides a fingerprint recognition device, wherein the fingerprint recognition device is an ultrasonic fingerprint recognition device, such as Figure 2 As shown, the fingerprint recognition device includes:

[0036] A first substrate 10, wherein the first substrate 10 has a first control circuit;

[0037] A piezoelectric layer (PVDF layer, i.e., polyvinylidene fluoride piezoelectric layer) 20, wherein the piezoelectric layer 20 is located on a first side surface of the first substrate 10;

[0038] an electrode layer 30, wherein the electrode layer 30 covers the piezoelectric layer 20 and electrically connects the first control circuit and the piezoelectric layer 20, so that the piezoelectric layer 20 can generate ultrasonic waves under the drive of the first control circuit;

[0039] A backing 40, wherein the backing 40 is located on a side of the electrode layer 30 away from the piezoelectric layer 20, so as to facilitate packaging from the side of the electrode layer 30 away from the piezoelectric layer 20, thereby preventing the piezoelectric layer 20 from being affected by moisture and oxygen in the external environment;

[0040] The encapsulation layer 50 covers the side wall of the backing 40, and the encapsulation layer 50, the backing 40 and the electrode layer 30 form a sealed cavity;

[0041] The bonding structure 60 is located in the sealing cavity. The bonding structure 60 includes at least one bonding layer. The bonding layer includes a plurality of bonding units, and there are gaps between adjacent bonding units.

[0042] It should be noted that, in the embodiment of the present application, at least one adhesive layer is arranged in the sealed cavity formed by the packaging layer, the backing and the electrode layer, and the adhesive layer includes a plurality of adhesive units, and there is a gap between adjacent adhesive units, so that the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing is reflected back and forth at the interface between the adhesive unit and the gap when it is transmitted to the inside of each adhesive unit in the at least one adhesive layer, so that the adhesive unit has a strong absorption effect on the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing, thereby greatly reducing the amount of reflected ultrasonic signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted to the side of the backing during the transmission process on the fingerprint recognition accuracy of the fingerprint recognition device.

[0043] Optionally, based on the above embodiment, in one embodiment of the present application, Figure 3 and Figure 4 As shown, the width w1 of the gap between adjacent bonding units ranges from 1 micron to 100 microns, including the end value, so as to increase the density of the bonding units in the packaging cavity while ensuring that the process capability allows, thereby improving the sound absorption effect of the bonding layer on ultrasound, thereby further reducing the amount of reflected ultrasonic signals generated by the part of the ultrasound generated by the piezoelectric layer that is transmitted to the backing side during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic signals on the fingerprint recognition accuracy of the fingerprint recognition device.

[0044] Based on any of the above embodiments, in one embodiment of the present application, continue as follows Figure 3 and Figure 4 As shown, within the plane where the bonding structure is located, the size range of the bonding unit w2 is 1 micron to 100 microns, including the end value, so as to increase the density of the bonding unit in the packaging cavity while ensuring that the process capability allows, thereby improving the sound absorption effect of the bonding layer on ultrasound, and further reducing the amount of reflected ultrasonic signal generated by the part of the ultrasound generated by the piezoelectric layer that is transmitted to the side of the backing during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic signal on the fingerprint recognition accuracy of the fingerprint recognition device.

[0045] It should be noted that Figure 3 and Figure 4Although two w1 and w2 are shown in the figure, w1 only represents the gap size between adjacent bonding units, and does not mean that the gap sizes between any two adjacent bonding units are the same. Similarly, w2 only represents the size of the bonding unit, and does not mean that the sizes between each bonding unit are the same. In practical applications, the gap size between any two adjacent bonding units can be the same or different, as long as it is within the value range of w1. Similarly, the sizes between each bonding unit can be the same or different, as long as it is within the value range of w2.

[0046] On the basis of any of the above embodiments, in one embodiment of the present application, the wavelength of the wave in the bonding unit is λ, and the dimension w2 of the bonding unit in the plane parallel to the first substrate satisfies λ / 10≤w2≤λ, so that the bonding layer has a sound absorption effect on the ultrasonic wave, thereby further reducing the amount of reflected ultrasonic wave signal generated by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted to the backing side during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic wave signal on the fingerprint recognition accuracy of the fingerprint recognition device. It should be noted that the wavelength of ultrasonic wave in different media is different, which is specifically related to the material properties of the medium. For example, the wavelength of ultrasonic wave in plastic ranges from 200 microns to 300 microns.

[0047] Based on any of the above embodiments, in one embodiment of the present application, the adhesive unit in the adhesive layer is a foamed adhesive unit, so that the adhesive unit has a plurality of holes inside, and then when the ultrasonic wave is transmitted to the inside of the adhesive unit, the absorption effect of the adhesive unit on the ultrasonic wave can be improved, but the present application does not limit this, and it depends on the specific situation.

[0048] On the basis of any of the above embodiments, in one embodiment of the present application, nitrogen is filled between adjacent bonding units, so that on the basis of ensuring that there is a gap between adjacent bonding units, the gap between adjacent bonding units is filled with nitrogen, thereby reducing the probability of moisture and oxygen existing in the sealed cavity, thereby further preventing the piezoelectric layer from being affected by moisture and oxygen in the external environment. However, the present application does not limit this, and in other embodiments of the present application, the gap between adjacent bonding units can also be filled with other gases that can isolate moisture and oxygen, depending on the specific situation.

[0049] Based on any of the above embodiments, in one embodiment of the present application, Figure 5As shown, the gaps between the adjacent bonding units are filled with a dry material to further ensure that there is no moisture and oxygen in the packaging cavity, thereby preventing the water and oxygen in the packaging cavity from affecting the piezoelectric layer through the electrode layer. Optionally, based on the above embodiment, in one embodiment of the present application, the dry material is silica gel, but the present application does not limit this. In other embodiments of the present application, the dry material can also be other materials, depending on the specific situation.

[0050] It should be noted that the inventor has found that when the length of the ultrasonic transmission path is less than 1 / 10 of the ultrasonic wavelength, the reflected wave formed by the ultrasonic transmission to the lower surface of the fingerprint recognition device can be ignored. Therefore, based on any of the above embodiments, in one embodiment of the present application, Figure 3 As shown, the thickness d of the portion of the electrode layer 30 between the bonding structure 60 and the piezoelectric layer 20 is less than 20 microns, so that the reflection effect of the electrode layer 30 on the ultrasonic wave generated by the piezoelectric layer 20 and transmitted to one side of the electrode layer 30 is negligible. Optionally, the thickness of the portion of the electrode layer between the bonding structure and the piezoelectric layer is less than 1 micron, so as to further reduce the thickness of the electrode layer, thereby further reducing the reflection effect of the electrode layer on the ultrasonic wave, and further reducing the influence of the second reflected wave reflected from the lower surface of the fingerprint recognition device on the fingerprint recognition accuracy of the fingerprint recognition device, thereby improving the fingerprint recognition accuracy of the fingerprint recognition device.

[0051] In the above embodiment, since the thickness of the electrode layer is relatively small, in an optional embodiment of the present application, the formation process of the electrode layer is a sputtering process or an evaporation process, so as to reduce the process difficulty when forming the electrode layer while ensuring that an electrode layer with a relatively small thickness can be formed. However, the present application does not limit this and it depends on the specific situation.

[0052] It should be noted that since the material of the piezoelectric layer will deteriorate in a high temperature environment, such as the deterioration point of polyvinylidene fluoride is in the range of 100°C-150°C, therefore, based on the above embodiment, in one embodiment of the present application, the process temperature when the electrode layer is formed is less than 100°C to ensure that the piezoelectric layer will not deteriorate and the working performance will not change during the formation of the electrode layer.

[0053] It should also be noted that, in any embodiment of the present application, the bonding structure may include one bonding layer or at least two bonding layers, and the present application does not limit this, depending on the specific circumstances.

[0054] Optionally, based on any of the above embodiments, in an embodiment of the present application, Figure 6 and Figure 7 As shown, the bonding structure 60 includes a first bonding layer and a second bonding layer, the first bonding layer includes a plurality of first bonding units 61, and gaps are provided between adjacent first bonding units 61, and the second bonding layer includes a plurality of second bonding units 62, and gaps are provided between adjacent second bonding units 62. By arranging multiple layers of bonding layers in the bonding structure 60, the absorption effect of the bonding structure on the ultrasonic waves emitted by the piezoelectric layer is improved.

[0055] Based on the above embodiment, in one embodiment of the present application, continue as follows Figure 7 As shown, the projection of the first bonding unit 61 in the first direction X and the projection of the second bonding unit 62 in the first direction X are arranged alternately, and the projection of the first bonding unit 61 in the second direction Y and the projection of the second bonding unit 62 in the second direction Y are arranged alternately, so that in the direction perpendicular to the plane where the backing is located, the first bonding unit is used to block at least part of the gap between adjacent second bonding units, and the second bonding unit is used to block at least part of the gap between adjacent first bonding units, thereby further improving the sound absorption effect of the bonding structure, while reducing the water-oxygen path in the bonding structure, and improving the ability of the bonding structure to block water-oxygen and oxygen. Wherein, the first direction and the second direction are both parallel to the plane where the bonding structure is located, and the first direction and the second direction intersect.

[0056] Optionally, based on the above embodiment, in one embodiment of the present application, Figure 8 As shown, in a direction perpendicular to the plane where the backing is located, the plurality of first bonding units 61 completely cover the gaps between adjacent second bonding units 62 among the plurality of second bonding units 62, and the plurality of second bonding units 62 completely cover the gaps between adjacent first bonding units 61 among the plurality of first bonding units 61, so as to further improve the sound absorption effect of the bonding structure and the ability of the bonding structure to block water oxygen and oxygen, but the present application does not limit this and it depends on the specific circumstances.

[0057] Based on any of the above embodiments, in one embodiment of the present application, when the bonding structure includes multiple bonding layers, such as Fig. 9 As shown, along the direction Z where the piezoelectric layer 20 moves away from the first substrate 10, the gap width between adjacent bonding units in the multi-layer bonding layer gradually decreases, such as W22 is smaller than W21, thereby reducing the width of the water-oxygen path in the bonding structure and improving the packaging effect of the piezoelectric layer. However, the present application does not limit this and it depends on the specific situation.

[0058] It should be noted that, based on any of the above embodiments, in one embodiment of the present application, the formation of the packaging layer needs to be carried out in a nitrogen environment to ensure a low water and oxygen concentration in the packaging cavity, thereby reducing the probability that the piezoelectric layer cannot work normally due to the influence of water and oxygen.

[0059] Based on any of the above embodiments, in one embodiment of the present application, Fig.10 and Fig.11 As shown, the bonding structure 60 also includes a bonding frame 63, and the bonding frame 63 is arranged around the at least one bonding layer. It should be noted that, since the bonding frame can form a closed space on the surface of the electrode layer, in the embodiment of the present application, when the bonding frame, the bonding layer and the backing are formed in a nitrogen environment, the low water and oxygen concentration in the sealed cavity can be guaranteed, so that in the embodiment of the present application, the formation of the encapsulation layer can be carried out in a natural environment, thereby reducing the process difficulty of the encapsulation layer, but the present application does not limit this, and it depends on the specific situation.

[0060] Based on any of the above embodiments, in one embodiment of the present application, Fig.12 As shown, the electrode layer 30 has multiple sides, and the multiple sides include a first side and a second side that are opposite to each other. The first control circuit is electrically connected to at least the first side of the electrode layer 30 to ensure the electrical connection between the first control circuit and the electrode layer 30; the encapsulation layer 50 covers at least the second side of the electrode layer 30 to protect the second side of the electrode layer.

[0061] Optionally, based on the above embodiment, in one embodiment of the present application, Fig.13 As shown, the multiple sides of the electrode layer also include a third side 33 and a fourth side 34 connecting the first side 31 and the second side 32. In this embodiment, the encapsulation layer 50 also extends to cover a portion of the third side 33 and the fourth side to protect the third side and the fourth side of the electrode layer.

[0062] It should be noted that, since the size of the electrode layer in the Y direction is relatively small, in an optional embodiment of the present application, the electrical connection area between the first control circuit and the electrode layer 30 also extends to the third side 33 and a part of the fourth side 34 to ensure the electrical connection performance between the first control circuit and the electrode layer 30 and reduce the process difficulty of realizing the electrical connection between the first control circuit and the electrode layer 30. However, the present application does not limit this, and it depends on the specific situation.

[0063] It should also be noted that in the embodiment of the present application, since the thickness of the electrode layer is relatively small, the step difference between the portion of the electrode layer located on the first substrate and the first substrate is relatively small. Therefore, when the packaging layer also covers the side of the electrode layer, the process difficulty during the formation of the packaging layer is relatively small and the packaging quality is relatively good.

[0064] Optionally, based on any of the above embodiments, in one embodiment of the present application, the packaging layer is a flexible material layer, so that the flexibility of the packaging layer is combined with the flexibility of the bonding structure to make the sealed cavity have good mechanical impact resistance, thereby ensuring that the sealed cavity will not be damaged by mechanical impact, and at the same time avoiding the backing and structures such as the electrode layer and the piezoelectric layer from being damaged by mechanical impact during the manufacturing process, thereby improving the yield of the fingerprint recognition device.

[0065] It should be noted that in an optional embodiment of the present application, the formation process of the encapsulation layer and / or the bonding structure is a coating process. Therefore, in the embodiment of the present application, the thickness of the sealing cavity can be less than 100 microns, and the process difficulty is relatively low.

[0066] Specifically, in one embodiment of the present application, the encapsulation layer includes a stacked plastic layer and a water- and oxygen-proof layer, wherein the plastic layer may be a polyethylene terephthalate (PET) layer, or a flexible layer such as polyimide film (PI), and the water- and oxygen-proof layer may be an organic layer, or an inorganic layer, such as a silicon dioxide layer, etc. The present application does not impose any limitation on this, and it depends on the specific circumstances.

[0067] Based on any of the above embodiments, in one embodiment of the present application, Fig.14 As shown, the projection of the backing 40 on the first substrate 10 completely covers the projection of the piezoelectric layer 20 on the first substrate 10 and the projection of the active devices in the first control circuit 11 on the first substrate 10, wherein the first control circuit 11 is located on the first substrate 10, so that the backing can cover the piezoelectric layer and the active devices in the first control circuit from the side of the backing away from the piezoelectric layer, thereby providing a better water-proof and oxygen-proof environment for the piezoelectric layer and the active devices in the first control circuit.

[0068] Specifically, in one embodiment of the present application, the first control circuit includes a scanning circuit and a gating circuit, wherein the scanning circuit is used to scan each row memory corresponding to the piezoelectric layer, and the gating circuit is used to read the data signal in each memory to form a fingerprint image. It should be noted that in the embodiment of the present application, the active device in the first control circuit includes at least the thin film transistor (TFT) in the scanning circuit and the gating circuit.

[0069] It should be noted that since the peripheral wiring in the first control circuit has a strong ability to resist water and oxygen, in the embodiment of the present application, the projection of the backing on the first substrate may cover the projection of the peripheral wiring in the first control circuit on the first substrate, or may not cover the projection of the peripheral wiring in the first control circuit on the first substrate, depending on the specific circumstances.

[0070] Based on any of the above embodiments, in one embodiment of the present application, continue as follows Fig.14 As shown, the fingerprint recognition device further includes: a circuit board 70, the circuit board 70 is bound to the first substrate 10, and is directly electrically connected to the first control circuit 11, that is, the circuit board 70 is directly connected to the first control circuit 11, and no other electrical connection elements are arranged in the middle, so as to reduce the connection impedance loss between the circuit board 70 and the first control circuit 11 and reduce the signal transmission loss. However, this application does not limit this, and it depends on the specific situation.

[0071] Based on any of the above embodiments, in one embodiment of the present application, Fig.15 As shown, the fingerprint recognition device further includes: a display panel 80, so that the fingerprint recognition device is integrated with a display function. Optionally, in the embodiment of the present application, the display panel 80 is located on the second side surface of the first substrate 10, and the second side is opposite to the first side, so that the fingerprint recognition device is an under-screen fingerprint recognition device, but the present application does not limit this, and it depends on the specific situation.

[0072] Specifically, based on the above embodiments, in one embodiment of the present application, the display panel is an OLED display panel, but the present application is not limited to this. In other embodiments of the present application, the display panel may also be other types of display panels, depending on the specific circumstances.

[0073] In summary, in the fingerprint recognition device provided by the embodiment of the present application, at least one bonding layer is arranged in the sealed cavity formed by the packaging layer, the backing and the electrode layer, and the bonding layer includes a plurality of bonding units, and there is a gap between adjacent bonding units, so that the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing is reflected back and forth at the interface between the bonding unit and the gap when it is transmitted to the inside of each bonding unit in the at least one bonding layer, so that the bonding unit has a strong absorption effect on the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing, thereby greatly reducing the amount of reflected ultrasonic wave signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing during the transmission process, so as to significantly reduce the influence of the reflected ultrasonic wave signal formed by the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the side of the backing during the transmission process on the fingerprint recognition accuracy of the fingerprint recognition device, thereby improving the fingerprint recognition accuracy.

[0074] The various parts in this manual are described in a combination of parallel and progressive ways. Each part focuses on the differences from other parts, and the same or similar parts between the various parts can be referenced to each other.

[0075] With respect to the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other, so that professionals in the field can implement or use the present application. Various modifications to these embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fingerprint recognition device, characterized in that: include: A first substrate, wherein the first substrate has a first control circuit; a piezoelectric layer, the piezoelectric layer being located on a first side surface of the first substrate; an electrode layer, the electrode layer covering the piezoelectric layer, electrically connecting the first control circuit and the piezoelectric layer, so that the piezoelectric layer can generate ultrasonic waves under the drive of the first control circuit, the electrode layer having a plurality of side edges, the plurality of side edges including a first side edge and a second side edge opposite to each other, and the first control circuit being electrically connected to at least the first side edge of the electrode layer; A backing, the backing being located on a side of the electrode layer away from the piezoelectric layer; an encapsulation layer, wherein the encapsulation layer covers the side wall of the backing, and the encapsulation layer, the backing and the electrode layer form a sealed cavity, and the encapsulation layer at least covers the second side of the electrode layer; The bonding structure is located in the sealing cavity, and the bonding structure includes at least one bonding layer, the bonding layer includes a plurality of bonding units, and there are gaps between adjacent bonding units, so that the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the backing side is reflected back and forth at the interface between the bonding unit and the gap when it is transmitted to the inside of each bonding unit in the at least one bonding layer, so that the bonding unit has a strong absorption effect on the part of the ultrasonic wave generated by the piezoelectric layer that is transmitted toward the backing side.

2. The fingerprint recognition device according to claim 1, characterized in that: Nitrogen is filled between adjacent bonding units.

3. The fingerprint recognition device according to claim 1, characterized in that: The thickness of a portion of the electrode layer located between the bonding structure and the piezoelectric layer is less than 20 micrometers.

4. The fingerprint recognition device according to claim 1, characterized in that: The width of the gap between adjacent bonding units ranges from 1 micron to 100 microns, including the end values.

5. The fingerprint recognition device according to claim 1, characterized in that: The gaps between adjacent bonding units are filled with dry material.

6. The fingerprint recognition device according to claim 5, characterized in that: The drying material is silica gel.

7. The fingerprint recognition device according to claim 1, characterized in that: The bonding unit has a plurality of holes therein.

8. The fingerprint recognition device according to claim 1, characterized in that: The bonding structure comprises a first bonding layer and a second bonding layer, wherein the first bonding layer comprises a plurality of first bonding units, and gaps are provided between adjacent first bonding units; and the second bonding layer comprises a plurality of second bonding units, and gaps are provided between adjacent second bonding units; The projection of the first adhesive unit in the first direction and the projection of the second adhesive unit in the first direction are arranged alternately, and the projection of the first adhesive unit in the second direction and the projection of the second adhesive unit in the second direction are arranged alternately; The first direction and the second direction are parallel to the plane where the bonding structure is located, and the first direction and the second direction intersect.

9. The fingerprint recognition device according to any one of claims 1 to 8, characterized in that: The bonding structure further comprises a bonding frame, and the bonding frame is arranged around the at least one bonding layer.

10. The fingerprint recognition device according to claim 1, characterized in that: The electrode layer is formed by a sputtering process or an evaporation process.

11. The fingerprint recognition device according to claim 1, characterized in that: The packaging layer is a flexible material layer.

12. The fingerprint recognition device according to claim 1, characterized in that: The projection of the backing on the first substrate completely covers the projection of the piezoelectric layer on the first substrate and the projection of the active devices in the first control circuit on the first substrate.

13. The fingerprint recognition device according to claim 1, characterized in that: Also includes: A circuit board is bound to the first substrate and is directly electrically connected to the first control circuit.

14. The fingerprint recognition device according to claim 1, characterized in that: Also includes: A display panel is located on a second side surface of the first substrate, wherein the second side is opposite to the first side.

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