Fingerprint recognition structure and display device

Abstract

The present disclosure provides a fingerprint recognition structure and a display device. The fingerprint recognition structure includes an acoustic wave transmitting module, a focusing acoustic lens, and an acoustic wave receiving module. The acoustic lens is located between the acoustic wave transmitting module and the acoustic wave receiving module. The acoustic wave emitted by the acoustic wave transmitting module is directed toward the acoustic lens. The acoustic wave transmitting module is arranged at the focal position of the acoustic lens. The acoustic wave receiving module is used to detect the intensity distribution of the acoustic wave emitted by the acoustic wave transmitting module and then reflected back by the finger surface after the acoustic wave is reflected by the finger surface after passing through the acoustic lens and the acoustic wave receiving module in sequence. The fingerprint recognition structure improves the flexibility of design.

Description

Technical Field

[0001] The present disclosure relates to the field of fingerprint recognition and display technology, and more specifically, to a fingerprint recognition structure and a display device. Background Art

[0002] The existing under-display fingerprint recognition solution is usually an acoustic wave fingerprint recognition solution. Specifically, a fingerprint recognition device is attached to the back of the display. The fingerprint recognition device consists of a three-layer structure of a stacked electrode array, a piezoelectric material layer, and a common electrode. The transmission and structure of the sound wave are completed by these three layers. More new types of under-screen acoustic wave fingerprint recognition solutions are needed. Summary of the invention

[0003] The present disclosure provides a fingerprint recognition structure and a display device to provide a new type of under-screen fingerprint recognition solution.

[0004] According to a first aspect of the present disclosure, a fingerprint recognition structure is provided, comprising: an acoustic lens configured to reduce the diffusion angle of sound waves; an acoustic wave transmitting module located at a focal position of the acoustic lens and configured to transmit sound waves toward the acoustic lens; and an acoustic wave receiving module located on a side of the acoustic lens away from the acoustic wave transmitting module and configured to receive sound waves reflected back from a finger surface.

[0005] In some embodiments, the sound wave emitting module is a point sound source.

[0006] In some embodiments, the point sound source includes a third electrode, a second piezoelectric material layer, and a fourth electrode stacked in sequence in a direction away from the acoustic lens.

[0007] In some embodiments, the material of the second piezoelectric material layer is lead zirconate titanate piezoelectric ceramic.

[0008] In some embodiments, a ratio of a maximum dimension of the second piezoelectric material layer in an extension direction of the plane in which the second piezoelectric material layer is located to a focal length of the acoustic lens is less than or equal to 0.3.

[0009] In some embodiments, the sound wave receiving module includes a first electrode, a first piezoelectric material layer, and a second electrode stacked in sequence in a direction toward the acoustic lens.

[0010] In some embodiments, the first electrode includes a plurality of first electrode units arranged in an array; and / or, the second electrode includes a plurality of second electrode units arranged in an array; and the first piezoelectric material layer has a planar structure.

[0011] In some embodiments, the material of the first piezoelectric material layer includes polyvinylidene fluoride.

[0012] In some embodiments, the acoustic lens includes a lens body and a filling medium located on a side of the lens body facing the acoustic wave emission module, and a surface of the lens body on a side away from the filling medium is a plane.

[0013] In some embodiments, the second electrode is adhered to the surface of the lens body on a side away from the sound wave emitting module by a first bonding adhesive.

[0014] In some embodiments, the acoustic impedance of the first bonding adhesive is greater than the acoustic impedance of the lens body and the second electrode, and the thickness of the first bonding adhesive is half the wavelength of the sound wave in the first bonding adhesive; or the acoustic impedance of the first bonding adhesive is between the acoustic impedance of the lens body and the acoustic impedance of the second electrode, and the thickness of the first bonding adhesive is 1 / 4 the wavelength of the sound wave in the first bonding adhesive.

[0015] In some embodiments, the lens body is a convex lens, and the sound velocity in the convex lens is smaller than the sound velocity in the filling medium.

[0016] In some embodiments, the lens body is a concave lens, and the internal sound velocity of the concave lens is greater than the internal sound velocity of the filling medium.

[0017] In a second aspect, a display device is provided, comprising a display panel and the fingerprint recognition structure according to the first aspect.

[0018] In some embodiments, the fingerprint recognition structure is located on a side away from a display surface of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is an overall layout diagram of a fingerprint recognition structure provided by an embodiment of the present disclosure and a display device in which it is involved;

[0020] Figure 2 In one embodiment Figure 1 The cross-sectional view of the overall layout diagram along line AA is shown;

[0021] Figure 3 In another embodiment Figure 1 The cross-sectional view of the overall layout diagram along line AA is shown;

[0022] Figure 4 In another embodiment Figure 1 The cross-sectional view of the overall layout diagram along line AA is shown;

[0023] The accompanying drawings are marked as follows: 1. acoustic wave transmitting module; 11. third electrode; 12. second piezoelectric material layer; 13. fourth electrode; 2. acoustic lens; 21. lens body in the shape of a concave lens; 22. filling medium; 23. lens body in the shape of a convex lens; 3. acoustic wave receiving module; 31. first electrode; 32. first piezoelectric material layer; 33. second electrode; 41. first bonding adhesive; 42. second bonding adhesive; 5. display panel; 51. thin film encapsulation layer; 52. display function layer; 53. substrate; 6. cover plate; 100. finger. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] See also Figure 1-Figure 3 An embodiment of the present disclosure provides a fingerprint recognition structure, including: an acoustic lens 2, configured to reduce the diffusion angle of sound waves; an acoustic wave transmitting module 1, located at the focal position of the acoustic lens 2, configured to transmit sound waves toward the acoustic lens 2; and an acoustic wave receiving module 3, located on a side of the acoustic lens 2 away from the acoustic wave transmitting module, configured to receive sound waves reflected back from the surface of a finger.

[0026] The arrows in the drawings indicate the direction of travel of the sound waves.

[0027] The diffusion angle of a sound wave can be defined as the angle formed between the two propagation directions of the sound wave that differ the most.

[0028] See also Figure 2 The diffusion angle of the part of the sound wave emitted by the sound wave emitting module 1 that reaches the sound lens 2 is an obtuse angle, and the diffusion angle of the sound wave emitted from the sound lens 2 is nearly 0°.

[0029] Since the sound wave transmitting module 1 is arranged at the focal position of the sound lens 2 , the divergent sound waves emitted by the sound wave transmitting module 1 are converted into plane waves after passing through the sound lens 2 .

[0030] A plane wave is a sound wave whose wavefront (i.e., the isophase plane of the wave) is a plane during propagation. That is, in a plane perpendicular to the propagation direction of the sound wave, the phase of the sound wave is the same. In this way, the phase of the echo after reaching the sound wave receiving module 3 is also the same, so the sound wave receiving module 3 can receive at the same time. Simplify the receiving timing of the receiving circuit.

[0031] The area where the actual sound wave transmitting module 1 transmits sound waves must have a certain volume. Here, the sound wave transmitting module 1 is located at the focal position of the sound lens 2, and it is not strictly limited to which specific part of the sound wave transmitting module 1 is located at the focal position of the sound lens 2. It is only necessary that the focal point of the sound lens 2 is located within the sound emission area of ​​the sound wave transmitting module 1.

[0032] Those skilled in the art can appropriately adjust the position of the acoustic wave emission module 1 according to the experimental results so that the acoustic wave obtained after the acoustic lens conversion is closer to a uniform plane wave. For example, it is stipulated that the distance difference between the geometric center of the contact part between the acoustic wave emission module 1 and the acoustic lens 2 and the focus of the acoustic lens 2 shall not exceed 20% of the focal length of the acoustic lens 2.

[0033] The sound wave as a plane wave passes through the sound wave receiving module 3 and is finally reflected back by the surface of the finger 100. The sound wave reflected back by the surface of the finger 100 is then detected by the sound wave receiving module 3, so that a processing device (not shown, such as a fingerprint recognition computing chip) external to the fingerprint recognition structure can infer the texture of the fingerprint based on the distribution of the sound wave signal.

[0034] by Figure 2 For example, for the peak of the fingerprint, the interface where the sound wave is reflected is the surface where the finger 100 and the cover plate 6 are in contact, and for the valley of the fingerprint, the interface where the sound wave is reflected is the surface where the air and the cover plate 6 are in contact. The two interfaces reflect the sound waves differently, so the positions of the fingerprint peaks and valleys can be inferred accordingly.

[0035] Since the transmission and reception of sound waves are completed by different modules, the selection of materials in the sound wave transmitting module 1 and the selection of materials in the sound wave receiving module 3 are also independent. Therefore, those skilled in the art can select materials with stronger sound wave transmission to make the sound wave transmitting module 1, and select materials that can be made into a larger area and have uniform and stable properties to make the sound wave receiving module 3. In this way, greater flexibility is provided for the design of the fingerprint recognition structure.

[0036] The sound wave emitting module 1 can be a point sound source, and its overall size should of course be as small as possible.

[0037] The acoustic wave transmitting module 1 may include a third electrode 11, a second piezoelectric material layer 12, and a fourth electrode 13 stacked in sequence in a direction away from the acoustic lens 2. The material of the second piezoelectric material layer 12 may be lead zirconate titanate piezoelectric ceramics. The piezoelectric constant of the lead zirconate titanate material is relatively large, usually hundreds of pC / N, for example, 300 to 500 pC / N, so that the lead zirconate titanate material has a strong transmitting ability. Other materials that can stably emit strong sound waves are also preferred materials.

[0038] It should be noted that the piezoelectric material used in the above sound wave transmitting module 1 and the sound wave receiving module 3 may also be other piezoelectric materials such as AlN, ZnO, etc.

[0039] The ratio of the maximum dimension of the second piezoelectric material layer 12 in the extension direction of the plane in which it is located to the focal length of the acoustic lens 2 is less than or equal to 0.3. In this way, the acoustic wave transmitting module 1 is closer to an ideal point sound source.

[0040] Figure 1 The acoustic wave emission module 1 shown is circular as a whole, and the maximum dimension is the diameter of the circle. Of course, it can also be rectangular as a whole, and the maximum dimension is the diagonal length of the rectangle. As long as its overall size is small enough. That is, under the premise of ensuring a certain acoustic wave emission intensity, the size of the acoustic wave emission module 1 is as small as possible.

[0041] The sound wave receiving module 3 is a planar structure as a whole, that is, it detects sound waves in a relatively large plane area.

[0042] The effective receiving area of ​​the sound wave receiving module 3 should be larger than the effective transmitting area of ​​the sound wave transmitting module 1. If the sound wave receiving module 3 is planar as a whole, the area of ​​the orthographic projection of the sound wave transmitting module 1 on the plane where the sound wave receiving module 3 is located should be smaller than the area of ​​the sound wave receiving module 1.

[0043] See also Figure 2 and Figure 3 The sound wave receiving module 3 includes a stacked first electrode 31 , a first piezoelectric material layer 32 , and a second electrode 33 .

[0044] In some embodiments, the first electrode 31 includes a plurality of first electrode units arranged in an array (i.e., small electrode blocks), and / or the second electrode 33 includes a plurality of second electrode units arranged in an array (i.e., small electrode blocks). That is, the first electrode 31 and the second electrode 33 may be a whole surface structure or may be divided into a plurality of electrode units, but at least one of them is an array structure.

[0045] Each electrode unit in the array structure may also be connected to a driving circuit (not shown) to output a driving voltage to these electrode units or detect the voltage on these electrode blocks.

[0046] The design of the driving circuit can be configured according to the prior art, and the present disclosure does not limit this.

[0047] The size and spacing of each electrode unit in the array structure determine the imaging resolution of fingerprint recognition. For example, the larger the size of the electrode unit and the larger the spacing between them, the lower the imaging resolution of fingerprint recognition.

[0048] For a common fingerprint recognition resolution of 500 PPI, the maximum side length of the first electrode unit or the second electrode unit (assuming they are rectangular) can usually be set between 40 um and 50 um. For a common fingerprint recognition resolution of 300 PPI, the maximum side length of the first electrode unit or the second electrode unit (assuming they are rectangular) can usually be set between 65 um and 75 um.

[0049] See also Figure 2 and Figure 3, wherein the first electrode 31 includes a plurality of first electrode units arranged in an array, and the second electrode 33 is a full-surface structure.

[0050] In some embodiments, the material of the first piezoelectric material layer 32 may be polyvinylidene fluoride (PVDF), which can be processed by a coating process to form a first piezoelectric material layer 32 with a larger area and uniform and stable properties. The piezoelectric coefficient of polyvinylidene fluoride is usually in the range of tens of pC / N.

[0051] In some embodiments, the material of the first electrode 31 can be a metal conductor or an organic conductor, such as copper, silver, molybdenum, and alloy materials thereof, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like.

[0052] In some embodiments, the material of the second electrode 33 can be a metal conductor or an organic conductor, such as copper, silver, molybdenum, and alloy materials thereof, poly (3,4-ethylenedioxythiophene) (ie, PEDOT), and the like.

[0053] In some embodiments, the material of the third electrode 11 can be a metal conductor or an organic conductor, such as copper, silver, molybdenum, and alloy materials thereof, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like.

[0054] In some embodiments, the material of the fourth electrode 13 can be a metal conductor or an organic conductor, such as copper, silver, molybdenum, and alloy materials thereof, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like.

[0055] The following combination Figure 1-Figure 3 The detailed structures of two specific acoustic lenses 2 are introduced, and those skilled in the art may also adopt other types of acoustic lenses 2 to achieve the purpose of the present disclosure.

[0056] The acoustic lens 2 includes lens bodies 21 and 23 and a filling medium 22 located on the side of the lens bodies 21 and 23 facing the acoustic wave emission module 1 , and the surface of the lens bodies 21 and 23 away from the filling medium 22 is a plane.

[0057] In some embodiments, Figure 2 As shown, the acoustic lens 2 includes a lens body 21 in the shape of a concave lens and a filling medium 22 located on the side of the lens body 21 facing the acoustic wave emission module 1 . The sound speed in the concave lens 21 is greater than the sound speed in the filling medium 22 .

[0058] The material of the lens body 21 is, for example, polystyrene (whose internal sound velocity is usually 2400m / s), metal, glass (whose internal sound velocity is about 6000m / s). The lens body 21 (and the lens body 23 described later) can be prepared by a molding process. The present application does not limit the material of the filling medium 22, as long as its sound velocity meets the above requirements and can be well combined with the surface of the lens body 21 facing the sound wave emission module 1. In this structure, the material of the filling medium 22 is, for example, nylon, polyethylene, polystyrene, rubber, Teflon, etc. According to Figure 1 At this viewing angle, the lower surface of the filling medium 22 is a plane, so it is easier to fit and fix with other components in structure. Figure 2 At the current viewing angle, the acoustic wave emission module 1 can be attached to the lower surface of the filling medium 22 .

[0059] In some embodiments, the second electrode 33 is adhered to the surface of the lens body 21 on the side facing away from the acoustic wave emitting module 1 by means of a first bonding adhesive 41 .

[0060] In some embodiments, the acoustic impedance of the first bonding adhesive 41 is greater than the acoustic impedance of the lens body 21 and the second electrode 33, and the thickness of the first bonding adhesive 41 is half the wavelength of the sound wave in the first bonding adhesive 41; or the acoustic impedance of the first bonding adhesive 41 is between the acoustic impedance of the lens body 21 and the acoustic impedance of the second electrode 33, and the thickness of the first bonding adhesive 41 is 1 / 4 of the wavelength of the sound wave in the first bonding adhesive 41. On the premise of meeting the above-mentioned sound velocity requirements, the material of the first bonding adhesive 41 is selected from existing thermal adhesives or pressure-sensitive adhesives, and the present disclosure does not make special restrictions on this. Taking thermal adhesive as an example, it can be: water-soluble adhesive, hot melt adhesive, solvent-based adhesive, emulsion adhesive, solvent-free liquid adhesive.

[0061] It should be noted that the structure of the sound wave receiving module 3 is not limited thereto, and any existing device capable of detecting the distribution law of sound waves can be used in the present disclosure. In this specific application environment, the thickness of the first bonding adhesive 41 is set to reduce the reflection loss of the sound wave at the surface of the sound wave receiving module 3 facing the acoustic lens 2.

[0062] See also Figure 3 The acoustic lens 2 includes a convex lens-shaped lens body 23 and a filling medium 22 located on the side of the lens body 23 facing the acoustic wave emission module 1 , and the internal sound velocity of the lens body 23 is smaller than the internal sound velocity of the filling medium 22 .

[0063] The material of the lens body 23 is, for example, Teflon (sound velocity is 1400 m / s) or organic glass (sound velocity is 1700 m / s). The present application does not limit the material of the filling medium 22, as long as its sound velocity meets the above requirements and can be well combined with the surface of the lens body 23 facing the sound wave emission module 1. In this structure, the material of the filling medium 22 is, for example, nylon, polyethylene, polystyrene, rubber, etc. Figure 2 From the current perspective, the lower surface of the filling medium 22 is a plane, so that it is easier to fit and fix with other components in structure.

[0064] In some embodiments, the sound wave receiving module 3 includes a stacked first electrode 31, a first piezoelectric material layer 32, and a second electrode 33, and the first electrode 31 includes a plurality of first electrode units arranged in an array; the second electrode 33 is adhered to the surface of the lens body 23 on the side facing away from the sound wave transmitting module 1 through a first bonding adhesive 41; the acoustic impedance of the first bonding adhesive 41 is greater than the acoustic impedance of the lens body 23 and the second electrode 33, and the thickness of the first bonding adhesive 41 is half the wavelength of the sound wave in the first bonding adhesive 41; or the acoustic impedance of the first bonding adhesive 41 is between the acoustic impedance of the lens body 23 and the acoustic impedance of the second electrode 33, and the thickness of the first bonding adhesive 41 is 1 / 4 the wavelength of the sound wave in the first bonding adhesive 41.

[0065] It should be noted that the structure of the sound wave receiving module 3 is not limited thereto, and any existing device capable of detecting the distribution law of sound waves can be used in the present disclosure. In this specific application environment, the thickness of the first bonding adhesive 41 is set to reduce the reflection loss of the sound wave at the surface of the sound wave receiving module 3 facing the acoustic lens 2.

[0066] above Figure 2 and Figure 3 In the two embodiments shown, another function of the filling medium 22 is to make the acoustic wave emission surface of the acoustic wave emission module 1 just near the focus of the acoustic lens 2. That is, to adjust the distance between the acoustic wave emission module 1 and the center of the acoustic lens 2.

[0067] for Figure 2 In the embodiment shown, the radius of curvature R of the lens body 21, the focal length L of the lens body 21, the sound velocity C1 in the filling medium 22, and the sound velocity C2 in the lens body 21 satisfy the following relationship:

[0068]

[0069] For example, the ratio of the sound velocity C1 in the filling medium to the sound velocity C2 in the lens body 21 is 0.5, the curvature radius R of the lens body 21 is 2.5 mm, and the lateral dimension of the lens body 21 can be controlled within 5 mm. However, the distance between the highest point of the lens body 21 and the sound wave emission module 1 should be maintained at 5 mm (specifically, this can be achieved by controlling the thickness of the filling medium 22).

[0070] And for Figure 2 In the embodiment shown, the radius of curvature r of the lens body 23, the focal length l of the lens body 23, the sound velocity c1 in the filling medium 22, and the sound velocity c2 in the lens body 23 satisfy the following relationship:

[0071]

[0072] An embodiment of the present disclosure provides a display device, including a display panel 5 and a fingerprint recognition structure, wherein the fingerprint recognition structure is the aforementioned fingerprint recognition structure.

[0073] Specifically, the display panel 5 is, for example, a light emitting diode display panel, which may be an organic light emitting diode display panel, or a quantum dot light emitting diode display panel.

[0074] See also Figure 2 and Figure 3 In some embodiments, the display panel 5 may be an organic light emitting diode display panel, wherein the substrate 53 may be a glass substrate, a plurality of organic light emitting diodes may be arranged in the display function layer 52, and the thin film encapsulation layer 51 may be an organic thin film encapsulation layer or an inorganic thin film encapsulation layer.

[0075] The present disclosure does not limit the specific structure of the display panel 5, and it can be configured according to the existing technology.

[0076] See also Figure 2 and Figure 3 In some embodiments, the fingerprint recognition structure is located on a side of the display surface away from the display panel 5. For example, the display panel 5 is located on the side of the sound wave receiving module 3 facing away from the acoustic lens 3, and the display surface of the display panel 5 faces away from the sound wave receiving module 3. In this way, under-screen fingerprint recognition can be achieved.

[0077] Specifically, the sound wave receiving module 3 can be first manufactured on the display panel 5 by deposition, photolithography and other processes, and then the sound wave receiving module 3 is adhered to the acoustic lens 2 by the first bonding adhesive 41. Of course, the fingerprint recognition structure can also be attached to the display panel 5 after the entire structure is manufactured.

[0078] The combination of the display panel and the fingerprint recognition structure is not limited thereto.

[0079] For example, in some embodiments, see Figure 4 The display panel 5 can be located between the sound wave receiving module 3 and the acoustic lens 2 , and the display surface of the display panel 5 faces the sound wave receiving module 3 .

[0080] Of course, in this embodiment, a transparent piezoelectric material, such as polyvinylidene fluoride (PVDF), needs to be used in the receiving module 3. In addition, the electrodes in the receiving module 3 also need to be made of a transparent conductive material, such as indium tin oxide.

[0081] In some embodiments, the sound wave receiving module 3 may also be integrated into the display panel 5 , that is, designed as an Incell solution.

[0082] Of course, the display device may further include a cover plate 6 to protect the display panel 5 .

[0083] The material of the cover plate 6 is glass, for example.

[0084] See also Figure 2 and Figure 3 The cover plate 6 is bonded to the display panel 5 via the second bonding adhesive 42 .

[0085] See also Figure 4 The cover plate 6 is bonded to the sound wave receiving module 3 through the second bonding adhesive 42 .

[0086] The second bonding adhesive 42 may be optical adhesive (OC).

[0087] See also Figure 1 Since the fingerprint recognition area of ​​a single fingerprint recognition structure is limited, multiple fingerprint recognition structures can be attached to a display panel 5. For example, the surface of the acoustic wave emission module 1 is a circle with a diameter of 1 mm, and a plane wave with a diameter of 5 mm is obtained after conversion by the acoustic lens 2. If a fingerprint recognition area with a diameter of 2 cm is required, 4 to 6 fingerprint recognition structures need to be set.

[0088] Of course, the acoustic lens 2 is usually circular in shape as a whole. Since multiple acoustic lenses 2 need to be spliced ​​together, their adjacent surfaces can be cut into planes to facilitate splicing of multiple acoustic lenses 2.

[0089] Of course, in order to prevent the multiple sound wave transmitting modules 1 from interfering with each other, the multiple sound wave transmitting modules 1 can be made to work in sequence, so that the corresponding detection areas of the sound wave receiving module 3 are detected in sequence.

[0090] Specifically, the display device is, for example, a display module, a mobile phone, a computer, a monitor, or any other product or component with a display function.

[0091] The embodiment of the present disclosure also provides a driving method of a fingerprint recognition structure, which is applied to the above-mentioned fingerprint recognition structure. Figure 2 or Figure 3Taking the fingerprint recognition structure shown in the figure as an example, the driving method includes: driving the sound wave transmitting module 1 to transmit sound waves; detecting the sound wave receiving module 3 to receive the sound waves reflected back by the finger. Figure 1 Taking as an example, the above process is repeatedly performed 4 times, so that the features of the fingerprints in the detection areas corresponding to the 4 acoustic wave emission modules 1 are detected.

[0092] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A fingerprint recognition structure, wherein: include: an acoustic lens configured to reduce the diffusion angle of the sound waves; an acoustic wave transmitting module, located at the focal position of the acoustic lens and configured to transmit acoustic waves toward the acoustic lens; an acoustic wave receiving module, located at a side of the acoustic lens away from the acoustic wave transmitting module, and configured to receive the acoustic wave reflected back from the surface of the finger; The acoustic lens comprises a lens body and a filling medium located on a side of the lens body facing the acoustic wave emission module, and a surface of the lens body on a side away from the filling medium is a plane.

2. The fingerprint recognition structure according to claim 1, wherein: The sound wave emission module is a point sound source.

3. The fingerprint recognition structure according to claim 2, wherein: The point sound source includes a third electrode, a second piezoelectric material layer, and a fourth electrode which are stacked in sequence in a direction away from the sound lens.

4. The fingerprint recognition structure according to claim 3, wherein: The material of the second piezoelectric material layer is lead zirconate titanate piezoelectric ceramic.

5. The fingerprint recognition structure according to claim 3, wherein: The ratio of the maximum dimension of the second piezoelectric material layer in the extension direction of the plane in which the second piezoelectric material layer is located to the focal length of the acoustic lens is less than or equal to 0.

3.

6. The fingerprint recognition structure according to claim 1, wherein: The sound wave receiving module includes a first electrode, a first piezoelectric material layer, and a second electrode which are sequentially stacked in a direction toward the acoustic lens.

7. The fingerprint recognition structure according to claim 6, wherein: The first electrode includes a plurality of first electrode units arranged in an array; and / or the second electrode includes a plurality of second electrode units arranged in an array; and the first piezoelectric material layer has a planar structure.

8. The fingerprint recognition structure according to claim 7, wherein: The material of the first piezoelectric material layer includes polyvinylidene fluoride.

9. The fingerprint recognition structure according to claim 6, wherein: The second electrode is adhered to the surface of the lens body on a side away from the sound wave emitting module by means of a first bonding adhesive.

10. The fingerprint recognition structure according to claim 9, wherein: The acoustic impedance of the first bonding adhesive is greater than the acoustic impedance of the lens body and the second electrode, and the thickness of the first bonding adhesive is half the wavelength of the sound wave in the first bonding adhesive; or the acoustic impedance of the first bonding adhesive is between the acoustic impedance of the lens body and the acoustic impedance of the second electrode, and the thickness of the first bonding adhesive is 1 / 4 the wavelength of the sound wave in the first bonding adhesive.

11. The fingerprint recognition structure according to claim 1, wherein: The lens body is a convex lens, and the sound velocity in the convex lens is smaller than the sound velocity in the filling medium.

12. The fingerprint recognition structure according to claim 1, wherein: The lens body is a concave lens, and the internal sound velocity of the concave lens is greater than the internal sound velocity of the filling medium.

13. A display device, wherein: It comprises a display panel and a fingerprint recognition structure according to any one of claims 1-12.

14. The display device according to claim 13, wherein: The fingerprint identification structure is located at a side away from the display surface of the display panel.

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