Ultrasonic sensor and display device including the same

Abstract

The present application relates to an ultrasonic sensor and a display device including the same. An ultrasonic sensor includes a substrate, a piezoelectric member disposed at the substrate, and an upper electrode disposed on the piezoelectric member, the upper electrode including silver paste.

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic sensor and a display device including the same, and more particularly to an ultrasonic sensor capable of recognizing biometric information of a user and a display device including the same. Background Art

[0002] In our information society, the demand for display devices for displaying images has increased in various forms. As display devices, various display devices such as liquid crystal displays (LCDs), organic light-emitting displays (OLEDs), and quantum dot light-emitting displays (QLEDs) are used.

[0003] Display devices are applied to various electronic devices such as smart phones, tablets, notebook computers, monitors, and TVs. In particular, recently, due to the development of mobile communication technology, portable electronic devices such as smart phones, tablets, and notebook computers have been increasingly used.

[0004] In addition to communication functions, portable electronic devices also store personal information such as contact information, call records, messages, photos, memos, the user's web surfing information, location information, and financial information. Therefore, in order to prevent personal information from leaking from portable electronic devices, various security methods for protecting personal information have been applied to portable electronic devices. Among security methods, fingerprint authentication permits the use of an electronic device based on the user's fingerprint, which is biometric information, and thus has higher security than other security methods such as password authentication or pattern authentication.

[0005] Fingerprint sensors for fingerprint authentication can be classified into optical fingerprint sensors, ultrasonic fingerprint sensors, infrared fingerprint sensors, and capacitive fingerprint sensors according to the working principle. An ultrasonic fingerprint sensor can identify a fingerprint by receiving ultrasonic waves generated by an ultrasonic generator and reflected from the user's fingerprint pattern via an ultrasonic receiver, and the user's fingerprint pattern includes valleys and ridges of the user's fingerprint.

[0006] However, in an ultrasonic sensor including a polyvinylidene fluoride (PVDF) film as a piezoelectric member and a display device including the ultrasonic sensor, structural defects caused by manufacturing processes or structural defects may occur in the upper electrode or the piezoelectric member, which deteriorates the reliability when applied to a display device or a portable electronic device. Summary of the Invention

[0007] An ultrasonic sensor and a display device including the same may have the following limitations: Structural defects caused by manufacturing processes or structural defects may occur in the upper electrode or the piezoelectric member.

[0008] Accordingly, the inventors of the present disclosure have invented an ultrasonic sensor including a top electrode and a piezoelectric member with stable structures and processes, and a display device including the same.

[0009] Accordingly, the present disclosure provides an ultrasonic sensor and a display device including the ultrasonic sensor, which substantially eliminate one or more problems caused by the limitations and disadvantages of the related art.

[0010] One aspect of the present disclosure provides an ultrasonic sensor including a top electrode and a piezoelectric member with stable structures and processes, and a display device including the same.

[0011] Another aspect of the present disclosure provides an ultrasonic sensor with excellent ultrasonic receiving and transmitting performance, and a display device including the same.

[0012] Additional features and aspects will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the inventive concepts provided herein. Other features and aspects of the inventive concepts may be realized and obtained by means of the structures particularly pointed out in the written description and claims thereof as well as the drawings (or structures derivable therefrom).

[0013] To achieve these and other aspects of the inventive concepts, as implemented and broadly described herein, an ultrasonic sensor includes: a substrate; a piezoelectric member disposed at the substrate; a top electrode disposed on the piezoelectric member, the top electrode including silver paste.

[0014] In another aspect of the present disclosure, an ultrasonic sensor includes: a piezoelectric member disposed on a substrate; a bottom electrode disposed below the piezoelectric member; a top electrode disposed to face the bottom electrode and disposed on the piezoelectric member; and a support member disposed between the substrate and the bottom electrode, the top electrode and the bottom electrode including silver paste.

[0015] In another aspect of the present disclosure, a display device includes: a cover member including a display area and an ultrasonic sensor area; a display device disposed on a rear surface of the cover member and overlapping with the display area; and an ultrasonic sensor disposed on the rear surface of the cover member and overlapping with the ultrasonic sensor area.

[0016] According to an embodiment of the present disclosure, an ultrasonic sensor and a display device including the same in which the piezoelectric member and the top electrode have stable structures and processes can be provided.

[0017] In addition, according to an embodiment of the present disclosure, an ultrasonic sensor and a display device including the same in which the sensitivity of transmitting and receiving ultrasonic waves is improved can be provided.

[0018] Other systems, methods, features and advantages will be, or will become, apparent to those of ordinary skill in the art upon review of the following figures and detailed description. All such additional systems, methods, features and advantages are intended to be included within this specification, within the scope of the present disclosure, and protected by the appended claims. Any content of this section should not be construed as a limitation on these claims. Other aspects and advantages are discussed in conjunction with the embodiments of the present disclosure.

[0019] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the inventive concept claimed.

[0020] Note 1. An ultrasonic sensor, the ultrasonic sensor comprising:

[0021] A substrate;

[0022] A piezoelectric member disposed at the substrate; and

[0023] An upper electrode disposed on the piezoelectric member,

[0024] wherein the upper electrode comprises silver paste.

[0025] Note 2. The ultrasonic sensor according to Note 1, wherein the substrate is electrically connected to the rear surface of the piezoelectric member.

[0026] Note 3. The ultrasonic sensor according to Note 1, wherein the ultrasonic sensor is configured to generate ultrasonic waves and receive reflected ultrasonic waves.

[0027] Note 4. The ultrasonic sensor according to Note 1, wherein the silver paste comprises silver epoxy resin or silver paint.

[0028] Note 5. The ultrasonic sensor according to Note 1, wherein the silver paste comprises silver nanoparticles and a resin binder.

[0029] Note 6. The ultrasonic sensor according to Note 5, wherein the silver paste comprises 90 to 95 wt% of the silver nanoparticles and 5 to 10 wt% of the resin binder.

[0030] Note 7. The ultrasonic sensor according to Note 5, wherein the silver nanoparticles have a size of 200 nm or less.

[0031] Note 8. The ultrasonic sensor according to Note 1, wherein the upper electrode is formed using the silver paste and an alcohol solvent.

[0032] Note 9. The ultrasonic sensor according to Note 1, wherein the surface roughness of the upper electrode is 0.01 μm or less.

[0033] Supplementary Note 10. The ultrasonic sensor according to Supplementary Note 1, wherein the thickness of the upper electrode is 10 μm or less.

[0034] Supplementary Note 11. The ultrasonic sensor according to Supplementary Note 1, wherein the piezoelectric member includes polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

[0035] Supplementary Note 12. The ultrasonic sensor according to Supplementary Note 1, wherein the substrate is a metal substrate, and the metal substrate is a brass substrate or an aluminum substrate.

[0036] Supplementary Note 13. The ultrasonic sensor according to Supplementary Note 1, further comprising:

[0037] a conductive adhesive member disposed between the substrate and the piezoelectric member,

[0038] wherein the conductive adhesive member includes at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

[0039] Supplementary Note 14. The ultrasonic sensor according to Supplementary Note 13, wherein the thickness of the conductive adhesive member is 5 μm or less.

[0040] Supplementary Note 15. The ultrasonic sensor according to Supplementary Note 1, further comprising:

[0041] an ultrasonic sensor controller disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor,

[0042] wherein the ultrasonic sensor controller includes:

[0043] a flexible printed circuit;

[0044] an ultrasonic sensor integrated circuit mounted on one side of the flexible printed circuit; and

[0045] a first wiring and a second wiring mounted on the other side of the flexible printed circuit and electrically connected to one surface and the other surface of the ultrasonic sensor.

[0046] Supplementary Note 16. The ultrasonic sensor according to Supplementary Note 15, wherein the first wiring contacts at least a part of the rear surface of the substrate, and the second wiring contacts at least a part of the side surface of the upper electrode.

[0047] Supplement 17. The ultrasonic sensor according to Supplement 16, wherein the second wiring is arranged to surround the upper electrode.

[0048] Supplement 18. The ultrasonic sensor according to Supplement 16, wherein the upper electrode is exposed at the uppermost part of the upper electrode.

[0049] Supplement 19. An ultrasonic sensor, comprising:

[0050] A piezoelectric member disposed on a substrate;

[0051] A lower electrode disposed under the piezoelectric member;

[0052] An upper electrode disposed to face the lower electrode and disposed on the piezoelectric member; and

[0053] A support member disposed between the substrate and the lower electrode,

[0054] wherein the upper electrode and the lower electrode comprise silver paste.

[0055] Supplement 20. The ultrasonic sensor according to Supplement 19, wherein the ultrasonic sensor includes a plurality of pixels, and each of the plurality of pixels includes the piezoelectric member, the lower electrode, and the upper electrode.

[0056] Supplement 21. The ultrasonic sensor according to Supplement 20, wherein each of the piezoelectric member, the lower electrode, and the upper electrode in each of the plurality of pixels is spaced apart from each other by a predetermined distance.

[0057] Supplement 22. The ultrasonic sensor according to Supplement 19, wherein the silver paste includes silver nanoparticles and a binder.

[0058] Supplement 23. The ultrasonic sensor according to Supplement 22, wherein the silver paste includes 90 to 95 wt% of the silver nanoparticles and 5 to 10 wt% of the binder.

[0059] Supplement 24. The ultrasonic sensor according to Supplement 22, wherein the silver nanoparticles have a size of 200 nm or less.

[0060] Supplement 25. The ultrasonic sensor according to Supplement 19, wherein the upper electrode and the lower electrode are formed using the silver paste and an ethanol-based solvent.

[0061] Supplement 26. The ultrasonic sensor according to Supplement 19, wherein the piezoelectric member includes polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

[0062] Supplementary Note 27. The ultrasonic sensor according to Supplementary Note 19, wherein the substrate is a plastic substrate.

[0063] Supplementary Note 28. The ultrasonic sensor according to Supplementary Note 19, wherein the support member comprises brass or aluminum.

[0064] Supplementary Note 29. The ultrasonic sensor according to Supplementary Note 19, further comprising:

[0065] a conductive adhesive member disposed between the substrate and the piezoelectric member,

[0066] wherein the conductive adhesive member comprises at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

[0067] Supplementary Note 30. The ultrasonic sensor according to Supplementary Note 29, wherein the conductive adhesive member comprises:

[0068] a first conductive adhesive member disposed in contact with the support member; and

[0069] a second conductive adhesive member disposed in contact with the lower electrode.

[0070] Supplementary Note 31. The ultrasonic sensor according to Supplementary Note 30, wherein the thickness of each of the first conductive adhesive member and the second conductive adhesive member is 5 μm or less.

[0071] Supplementary Note 32. The ultrasonic sensor according to Supplementary Note 19, further comprising:

[0072] an ultrasonic sensor controller disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor,

[0073] wherein the ultrasonic sensor controller comprises:

[0074] a flexible printed circuit;

[0075] an ultrasonic sensor integrated circuit mounted on one side of the flexible printed circuit; and

[0076] a first wiring and a second wiring mounted on the other side of the flexible printed circuit and electrically connected to the surface of the ultrasonic sensor.

[0077] Supplementary Note 33. The ultrasonic sensor according to Supplementary Note 32, wherein the first wiring is disposed between the substrate and the lower electrode, and the second wiring contacts at least a part of the side surface of the upper electrode.

[0078] Supplementary Note 34. A display device, comprising:

[0079] A covering member including a display area and an ultrasonic sensor area;

[0080] A display device disposed on the rear surface of the covering member and overlapping with the display area; and

[0081] The ultrasonic sensor according to any one of Supplementary Notes 1 to 33, the ultrasonic sensor being disposed on the rear surface of the covering member and overlapping with the ultrasonic sensor area. Brief Description of the Drawings

[0082] The drawings are included to provide a further understanding of the present disclosure and are incorporated into and constitute a part of this application. The drawings illustrate embodiments of the present disclosure and, together with the description, are used to explain the principles of the present disclosure.

[0083] Figure 1 is a cross-sectional view of an ultrasonic sensor according to an embodiment of the present disclosure;

[0084] Figure 2 is a cross-sectional view of an ultrasonic sensor according to another embodiment of the present disclosure;

[0085] Figure 3A and Figure 3B illustrates an array structure of an ultrasonic sensor according to an embodiment of the present disclosure;

[0086] Figure 4 is a perspective view of a portable electronic device including an ultrasonic sensor area;

[0087] Figure 5 is a cross-sectional view of the portable electronic device;

[0088] Figure 6 and Figure 7 illustrates display devices including ultrasonic sensors according to an embodiment and another embodiment of the present disclosure;

[0089] Figure 8A and Figure 8B is the result of measuring the surface roughness and thickness of the upper electrode according to an embodiment of the present disclosure;

[0090] Figure 9A and Figure 9B is the result of measuring the surface roughness and thickness of the upper electrode according to an experimental example;

[0091] Figure 10A are the results of measuring phase and impedance according to frequency of an ultrasonic sensor according to an embodiment of the present disclosure;

[0092] Figure 10B and Figure 10C are the results of measuring impedance according to the presence or absence of a reflector at the upper part of the ultrasonic sensor according to an embodiment of the present disclosure;

[0093] Figure 11A show the results of measuring phase and impedance according to frequency of an ultrasonic sensor according to another embodiment of the present disclosure;

[0094] Figure 11B and Figure 11C show the results of measuring impedance according to the presence or absence of a reflector at the upper part of the ultrasonic sensor according to another embodiment of the present disclosure;

[0095] Figures 12 to 26 is a cross-sectional view of an ultrasonic sensor according to various examples;

[0096] Figure 27 shows Figures 12 to 26 the pulse generator (pulser)-receiver measurement waveform of

[0097] Figure 28 shows Figure 19 the results of measuring phase and impedance according to frequency of an ultrasonic sensor of an experimental example of

[0098] Figure 29 shows Figure 19 the pulse generator-receiver transmission waveform of an experimental example of

[0099] Figure 30 shows Figure 25 the results of measuring phase and impedance according to frequency of an ultrasonic sensor of an experimental example of

[0100] Figure 31 shows Figure 26 the results of measuring phase and impedance according to frequency of an ultrasonic sensor of an experimental example of

[0101] Figures 32A to 32E is a diagram illustrating the process of a method for manufacturing an ultrasonic sensor according to another embodiment of the present disclosure.

[0102] Throughout the drawings and the detailed description, unless otherwise described, the same reference numerals should be understood to refer to the same elements, features, and structures. The relative dimensions and descriptions of these elements may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0103] Reference will now be made in detail to embodiments of the present disclosure, examples of which may be shown in the accompanying drawings. In the following description, when a detailed description of well-known functions or configurations related to this document is determined to unnecessarily obscure the gist of the inventive concept, the detailed description will be omitted. The progress of the described processing steps and / or operations is an example. However, the order of the steps and / or operations is not limited to the order set forth herein and may be changed as known in the art, except for steps and / or operations that must occur in a specific order. Like reference numerals identify like elements throughout. The names of the corresponding elements used in the following description are merely selected for convenience in writing the specification and may therefore be different from the names used in actual products.

[0104] Advantages and features of the present disclosure and methods for realizing them will be clarified by the embodiments described below in conjunction with the accompanying drawings. However, the present disclosure may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art. Furthermore, the present disclosure is only defined by the scope of the claims.

[0105] The shapes, sizes, ratios, angles, and quantities disclosed in the drawings used to describe the embodiments of the present disclosure are merely examples, and thus the present disclosure is not limited to the illustrated details. Like reference numerals always refer to like elements. In the following description, when a detailed description of related well-known functions or configurations is determined to unnecessarily obscure the key points of the present disclosure, the detailed description will be omitted. When using "comprising", "having", and "including" described in the present disclosure, another component may be added unless "only ~" is used. Unless otherwise specified, terms in the singular form may include the plural form.

[0106] When interpreting an element, the element is interpreted as including an error range or tolerance range, although there is no explicit description of these error or tolerance ranges.

[0107] When describing positional relationships, for example, when the positional relationship between two components is described as, for example, "on...", "above...", "below...", and "next to...", one or more other components may be provided between the two components unless more restrictive terms such as "exactly" or "directly" are used.

[0108] When describing temporal relationships, for example, when a time sequence is described as, for example, "after...", "subsequently...", "next", and "before...", discontinuous cases may be included unless more restrictive terms such as "exactly" or "directly" are used.

[0109] It will be understood that although terms such as "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0110] When describing the elements of the present disclosure, terms such as "first", "second", "A", "B", "(a)", "(b)", etc. may be used. These terms are intended to identify the corresponding elements from other elements, and the nature, order or quantity of the corresponding elements should not be limited by these terms. The expression that an element or layer is "connected", "coupled" or "bonded" to another element or layer means that the element or layer can not only be directly connected or bonded to another element or layer, but also be indirectly connected or bonded to another element or layer, where one or more intermediate elements or layers are "disposed" or "interposed" between the element or layer, unless otherwise specified.

[0111] The term "at least one" should be understood to include any and all combinations of one or more of the associated listed items. For example, the meaning of "at least one of the first element, the second element and the third element" represents all combinations of two or more of the first item, the second item and the third item and the first item, the second item or the third item.

[0112] The features of various embodiments of the present disclosure can be partially or wholly coupled or combined with each other, and can interoperate with each other in various ways and be technically driven, as can be fully understood by those skilled in the art. The embodiments of the present disclosure can be implemented independently of each other, or can be implemented together in a mutually dependent relationship.

[0113] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, all components of each ultrasonic sensor and each display device having the ultrasonic sensor according to all embodiments of the present disclosure are operatively coupled and configured. For the sake of convenience of description, the dimensions of each element illustrated in the drawings are different from the actual dimensions, and thus are not limited to the dimensions shown in the drawings.

[0114] Figure 1 An ultrasonic sensor according to an embodiment of the present disclosure is illustrated.

[0115] Referring to Figure 1 , an ultrasonic sensor 1 according to an embodiment of the present disclosure includes a substrate 11, a piezoelectric member 14 disposed on the substrate 11, an upper electrode 16 disposed on the upper surface of the piezoelectric member 14, and a conductive adhesive member 13 disposed between the substrate 11 and the piezoelectric member 14.

[0116] The substrate 11 may be at least one of a metal substrate, a plastic substrate, and a glass substrate.

[0117] When using a metal substrate as the substrate 11, it may include at least one of a brass substrate and an aluminum substrate, but the embodiments of the present disclosure are not limited thereto.

[0118] In addition, when using a metal substrate as the substrate 11, the support member 18 to be described later (for example, see Figure 2 ) may not be used, and the substrate 11 may simultaneously perform the functions of the substrate and the support member 18.

[0119] When using a plastic substrate as the substrate 11, it may be a polyimide substrate, but the embodiments of the present disclosure are not limited thereto.

[0120] When using a glass substrate as the substrate 11, it may be indium tin oxide (ITO) glass, but the embodiments of the present disclosure are not limited thereto.

[0121] A brass substrate may be used as the substrate 11 in the ultrasonic sensor 1 according to an embodiment of the present disclosure. When the brass substrate is used as the substrate 11, it may be configured to have a thickness of about 1.0 mm and may achieve the functions of ultrasonic transmission and reception without the configuration of the support member 18 described in Figure 2 .

[0122] In addition, the ultrasonic sensor 1 according to an embodiment of the present disclosure may be configured without a lower electrode. Therefore, an electrical signal may be applied to the piezoelectric member 14 via the substrate 11 in contact with the first wiring 43.

[0123] The piezoelectric member 14 may be a film-type piezoelectric member including ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer. In the ultrasonic sensor 1 according to an embodiment of the present disclosure, the piezoelectric member 14 may not be limited to the above materials, and materials capable of converting electrical energy into mechanical energy through the piezoelectric phenomenon and the inverse piezoelectric phenomenon to generate ultrasonic waves with a predetermined frequency and converting mechanical energy into electrical energy may be used without limitation.

[0124] According to an embodiment of the present disclosure, the piezoelectric member 14 may be a film-type piezoelectric member compressed or stretched by rotation in one direction, and according to an embodiment of the present disclosure, the piezoelectric member 14 may have a thickness of 10 to 50 μm.

[0125] The conductive adhesive member 13 can be disposed between the substrate 11 and the piezoelectric member 14, can bond the substrate 11 and the piezoelectric member 14, and can be electrically connected to the substrate 11 and the piezoelectric member 14 to each other. The conductive adhesive member 13 can include at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet (UV) adhesive, but the embodiments of the present disclosure are not limited thereto.

[0126] According to an embodiment of the present disclosure, the thickness of the conductive adhesive member 13 can be 5 μm or less. When the thickness of the conductive adhesive member 13 exceeds 5 μm, the ultrasonic transmission / reception efficiency may be reduced.

[0127] According to an embodiment of the present disclosure, the upper electrode 16 can be an electrode including silver (Ag). For example, when the upper electrode 16 is used as a solid metal including silver (Ag), due to the damping effect of the ultrasonic characteristics of the ultrasonic sensor 1 caused by the difference in physical properties from the piezoelectric member 14, ultrasonic waves may be attenuated or the intensity of the center frequency may be reduced. Therefore, the upper electrode 16 according to an embodiment of the present disclosure can be a silver paste (Ag paste). For example, the silver paste can be a silver paint or a silver epoxy resin. Here, the silver paint or the silver epoxy resin can be a material including both silver nanoparticles and a binder. The binder can contain a resin.

[0128] Each silver nanoparticle can have a size of 200 nm or less. When the size of the silver nanoparticles is 200 nm or less, the ultrasonic sensor can have transmission and reception performance due to the increased surface area according to the refinement of the silver nanoparticles.

[0129] The silver paste can include 90 to 95 wt% of silver nanoparticles and 5 to 10 wt% of a binder. If the silver paste has less than 90 wt% of silver nanoparticles, there may be a problem of reduced conductivity of the electrode.

[0130] The upper electrode 16 can be prepared by performing a screen printing process or a spraying process on a solvent in which silver (Ag) paste is diluted, and the upper electrode 16 can be prepared as an ethanol-based solvent (e.g., an alcohol solvent) without using harmful organic solvents such as ketone-based solvents used in a solution process.

[0131] Here, the binder can be a silver epoxy resin (Ag Epoxy) or a silver paint (Ag paint). Since the upper electrode 16 according to an embodiment of the present disclosure includes silver and a binder, referring to Table 1 below, the acoustic impedance can be based on the mixing ratio of silver and the binder, and the difference from the piezoelectric member 14 located below the upper electrode 16 is reduced, thereby improving the transmission and reception performance of ultrasonic waves.

[0132] [Table 1]

[0133]

[0134] Thus, when the upper electrode 16 includes a silver (Ag) paste, the upper electrode 16 can ultimately be configured to include a composite structure of silver (Ag) particles and a binder after undergoing the above-described solution-based coating and drying processes.

[0135] Alternatively, according to another embodiment of the present disclosure, the upper electrode 16 can be prepared by a screen printing process or a spraying process based on a solvent-free composition without a solvent.

[0136] If the upper electrode 16 uses a ketone-based solvent and the piezoelectric member 14 uses a film-type PVDF-based material, physical deformation of the piezoelectric member may occur during the drying process of the upper electrode, which may result in a limitation that the adhesion force to the object to which the ultrasonic sensor is attached is weakened.

[0137] The thickness of the upper electrode 16 can be 10 μm or less.

[0138] If the thickness of the upper electrode 16 exceeds 10 μm, the ultrasonic attenuation effect of the upper electrode 16 increases. As a result, the transmission and reception performance of the ultrasonic sensor 1 may deteriorate.

[0139] Furthermore, if the thickness of the upper electrode 16 exceeds 10 μm, a corrugation phenomenon may occur in which the ultrasonic radiation energy is divided into two bands in the portion where the frequency response is maximum, and as a result, the transmission and reception performance of the ultrasonic sensor 1 may deteriorate or decrease.

[0140] The surface roughness of the upper electrode 16 can be 0.01 μm or less. Here, the surface of the upper electrode 16 can be the upper surface facing the user 3 (e.g., the finger of the user 3).

[0141] The upper electrode 16 according to an embodiment of the present disclosure can have a surface roughness of 0.01 μm or less and can be configured to have a flat surface. The ultrasonic sensor according to an embodiment of the present disclosure includes an upper electrode 16 having an upper surface with a low surface roughness, thereby reducing scattering in random directions occurring on the surface of the upper electrode 16. Therefore, since the ultrasonic sensor 1 according to an embodiment of the present disclosure includes an upper electrode 16 having a surface roughness of 0.01 μm or less, losses caused by surface scattering of the upper electrode 16 can be reduced when receiving ultrasonic waves generated by the piezoelectric member 14 or ultrasonic waves reflected from the user 3.

[0142] According to an embodiment of the present disclosure, the ultrasonic sensor 1 may further include an ultrasonic sensor controller 4 configured to control the ultrasonic sensor 1.

[0143] The ultrasonic sensor controller 4 may include an ultrasonic sensor integrated circuit 41 and a flexible printed circuit 42, and may include a first wiring 43 and a second wiring 44 configured to apply signals to the ultrasonic sensor 1 through the flexible printed circuit 42.

[0144] The ultrasonic sensor integrated circuit 41 may be electrically connected to the ultrasonic sensor 1 to control the driving of the ultrasonic sensor 1 and read or decode the fingerprint pattern of the user 3 recognized by the ultrasonic sensor 1. The ultrasonic sensor integrated circuit 41 may be provided in the form of an integrated fingerprint sensor driving unit configured to drive the ultrasonic sensor 1 and a readout integrated circuit for reading or decoding the user biometric information detected by the ultrasonic sensor 1 and outputting it as a digital value. The ultrasonic sensor integrated circuit 41 may be electrically connected to the ultrasonic sensor 1 to control the generation and reception of ultrasonic waves during a first operation period configured to generate ultrasonic waves and a second operation period configured to receive ultrasonic waves, and analyze the data of the received reflected ultrasonic waves to identify fingerprints.

[0145] The flexible printed circuit 42 may be electrically connected to the ultrasonic sensor integrated circuit 41 and the ultrasonic sensor 1, and the flexible printed circuit 42 may have a predetermined circuit pattern formed thereon and may be formed of a heat-resistant plastic including polyimide and polyester as flexible materials.

[0146] The first wiring 43 may be provided at the rear surface of the substrate 11 and may be provided to at least partially overlap the substrate 11. When the ultrasonic sensor 1 includes a plurality of pixels, the ultrasonic sensor 1 may include a plurality of first wirings 43 for independently driving each of the plurality of pixels.

[0147] The second wiring 44 may be provided at the upper surface of the piezoelectric member 14 and may be provided to be electrically connected to the upper electrode 16. The second wiring 44 may include a plurality of second wirings 44 for independently driving each of the plurality of pixels when the ultrasonic sensor 1 includes a plurality of pixels.

[0148] will be described later with reference to Figure 3A and Figure 3B the array structures of the first wiring 43 and the second wiring 44.

[0149] According to an embodiment of the present disclosure, the first wiring 43 and the second wiring 44 may be formed of a copper tape having high conductivity, but the embodiments of the present disclosure are not limited thereto.

[0150] According to an embodiment of the present disclosure, the ultrasonic sensor 1 may further include a pressing plate 2 configured to cover the ultrasonic sensor 1 and the ultrasonic sensor controller 4. The pressing plate 2 may be a covering substrate exposed to the user facing the ultrasonic sensor 1. As Figure 1As shown, the body of user 3 can be in contact with the upper surface of the pressing plate 2. Here, the body of user 3 can be the fingerprint of the finger of user 3 including identification information.

[0151] The pressing plate 2 may not be necessary for the configuration of the ultrasonic sensor 1 according to an embodiment of the present disclosure, and the pressing plate 2 can be omitted when the ultrasonic sensor 1 according to an embodiment of the present disclosure is attached to another electronic device or object and used.

[0152] When ultrasonic waves are transmitted by driving the ultrasonic sensor to be described later, the piezoelectric member 14 can output ultrasonic waves to the front or rear of the piezoelectric member 14. The ultrasonic waves output to the front of the piezoelectric member 14 can be output to the outside of the pressing plate 2 through predetermined reflection, transmission, and absorption while passing through other components or media provided at the upper part of the piezoelectric member.

[0153] Figure 2 An ultrasonic sensor according to another embodiment of the present disclosure is illustrated.

[0154] Referring to Figure 2 , an ultrasonic sensor according to another embodiment of the present disclosure may include a substrate 11, a support member 18, conductive adhesive members 13a and 13b, a lower electrode 12, a piezoelectric member 14, an upper electrode 16, and a counter substrate 19, and compared with the ultrasonic sensor 1 according to the embodiment of the present disclosure in Figure 1 , the ultrasonic sensor according to another embodiment of the present disclosure may further include a lower electrode 12, a plurality of conductive adhesive members 13a and 13b, and a counter substrate 19. In the ultrasonic sensor 1 according to another embodiment of the present disclosure, Figure 1 the conductive adhesive members 13a, the piezoelectric member 14, and the upper electrode 16 described in

[0155] According to another embodiment of the present disclosure, a plastic substrate can be used as the substrate 11 in the ultrasonic sensor 1. When the plastic substrate is used as the substrate 11, it can be prepared as a polyimide substrate having a thickness of about 0.2 mm.

[0156] In addition, in the ultrasonic sensor 1 according to another embodiment of the present disclosure, when the support member 14, the lower electrode 12, the piezoelectric member 14, and the upper electrode 16 are adjusted to have horizontal and vertical dimensions smaller than those of the substrate 11, the support member 14, the lower electrode 12, the piezoelectric member 14, and the upper electrode 16 can be arranged to be aligned at the center of the substrate 11.

[0157] The lower electrode 12 can be configured to be the same as the upper electrode 16 described in reference to Figure 1 .

[0158] Therefore, when the lower electrode 12 includes silver (Ag), a silver (Ag) paste including silver (Ag) nanoparticles, a solvent, a binder, etc. can be prepared by a screen printing process or a spraying process, and the silver (Ag) paste can be prepared as an ethanol-based solvent so as not to use harmful organic solvents such as ketone solvents.

[0159] Therefore, when the lower electrode 12 includes the silver (Ag) paste, the lower electrode 12 can finally be configured as a composite structure including the silver (Ag) paste and a binder after undergoing the above-described solution-based coating and drying processes.

[0160] Alternatively, according to another embodiment of the present disclosure, the lower electrode 12 can be configured by a screen printing process or a spraying process based on a solvent-free one that does not include a binder.

[0161] In addition, the ultrasonic sensor according to an embodiment of the present disclosure may further include a support member 18. When the substrate 11 of the ultrasonic sensor 1 is configured to include a metal, the support member 18 can be omitted or can be provided briefly.

[0162] The support member 18 can include a metal and can include at least one of brass and aluminum (Al), but the embodiments of the present disclosure are not limited thereto.

[0163] For example, the support member 18 can be an aluminum plate of about 0.2 mm and can be prepared to have horizontal and vertical dimensions corresponding to those of the piezoelectric member 14.

[0164] In addition, when aluminum is used as the support member 18, a black anodizing treatment can be additionally performed on the support member 18. Here, the black anodizing can be coloring to black by anodization.

[0165] The support member 18 can be disposed between the substrate 11 and the piezoelectric member 14 and can have dimensions corresponding to those of the piezoelectric member 14.

[0166] According to another embodiment of the present disclosure, the ultrasonic sensor 1 may further include an ultrasonic sensor controller 4 configured to control the ultrasonic sensor 1.

[0167] The ultrasonic sensor controller 4 can include an ultrasonic sensor integrated circuit 41 and a flexible printed circuit 42, and can include a first wiring 43 and a second wiring 44 configured to apply a signal to the ultrasonic sensor 1 through the flexible printed circuit 42.

[0168] Here, the first wiring 43 can be electrically connected to the lower electrode 12 through a second conductive adhesive member 13b, and the second wiring 44 can be disposed to surround the upper electrode 16. Therefore, the ultrasonic sensor 1 according to another embodiment of the present disclosure can have a structure in which the upper electrode 16 is exposed at the uppermost part.

[0169] The ultrasonic sensor according to another embodiment of the present disclosure may further include a counter substrate 19. The counter substrate 19 may be disposed on the upper electrode 16 and the second wiring 44, and may be prepared in a form in which a region corresponding to the region of the piezoelectric member 14 or the upper electrode 16 is open. Accordingly, a predetermined air layer may exist on the upper portion of the upper electrode 16. The counter substrate 19 may be adjusted to have the same thickness as that of the substrate 11, but the thickness of the counter substrate 19 is not limited to the same thickness as that of the substrate 11.

[0170] In the ultrasonic sensors according to the embodiments and other embodiments of the present disclosure, the signal received after transmitting ultrasonic waves may be detected as 6 dB (decibels) or higher.

[0171] The ultrasonic sensors according to the embodiments and other embodiments of the present disclosure may be driven as follows.

[0172] During a first operation period (ultrasonic wave generation period), an alternating current (AC) voltage may be applied to at least one of the first wiring 43 and the second wiring 44 by the ultrasonic sensor controller 4, and ultrasonic waves having a predetermined frequency range may be generated according to the contraction and expansion based on the piezoelectric effect of the piezoelectric member 14. The ultrasonic waves may be output to the upper surface or the lower surface of the piezoelectric member 14, and the ultrasonic waves emitted to the upper surface of the piezoelectric member 14 may contact the fingerprint of the user 3 to generate predetermined reflected ultrasonic waves.

[0173] In a second operation period (ultrasonic wave detection period), the ultrasonic waves reflected by the fingerprint of the user 3 or other media may reach the piezoelectric member 14 and the piezoelectric effect is reversible. Therefore, when a certain ultrasonic wave is applied to the piezoelectric member 14, a voltage may be generated according to the vibration, and the generated voltage may be recognized as a fingerprint pattern by the ultrasonic sensor controller 4. In Figure 1 and Figure 2 the ultrasonic sensor, since the piezoelectric member 14 serves as both an ultrasonic wave transmitter and an ultrasonic wave receiver at the same time, the piezoelectric member 14 may be referred to as a transceiver.

[0174] Here, the fingerprint of the user 3 may be formed by lines such that it has a unique pattern of an individual including valleys 31 and ridges 32 or a plurality of valleys 31 and ridges 32. When the user 3 (for example, a part of the user's finger) touches the platen 2 for fingerprint recognition, when the fingerprint of the user 3 having valleys 31 and ridges 32 touches one surface covering the platen 2, the ultrasonic sensor 1 recognizes the contact of the user 3, outputs ultrasonic waves to the user, and recognizes the fingerprint based on the impedance value of the reflected ultrasonic waves.

[0175] According to an embodiment of the present disclosure, the ultrasonic wave generated by the piezoelectric member 14 may be a plane wave traveling parallel to one surface of the piezoelectric member 14 arranged in a plate shape, and may be a diffused wave that radially diffuses and travels without a direction.

[0176] Figure 3A and Figure 3B illustrates Figure 1 and Figure 2 the array structure of the ultrasonic sensor.

[0177] Referring to Figure 3A and Figure 3B the ultrasonic sensor 1 including the piezoelectric member 14 and the upper electrode 16 may have an array structure in which a plurality of ultrasonic sensors are arranged to configure a plurality of ultrasonic sensor picture structures on the substrate 11.

[0178] As Figure 3A shown, the first wiring 43 may be configured as a common wiring commonly electrically connected to a plurality of ultrasonic sensors 1 or a plurality of piezoelectric members 14. The second wiring 44 may be configured to individually connect each of the plurality of ultrasonic sensors 1 or a plurality of upper electrodes 16.

[0179] As Figure 3B shown, the first wiring 43 may be configured as a common wiring commonly electrically connected to each of the plurality of ultrasonic sensors 1 or a plurality of piezoelectric members 14 arranged side by side in one direction (X). The second wiring 44 may be configured as a common wiring commonly electrically connected to each of the plurality of ultrasonic sensors 1 or a plurality of piezoelectric members 14 arranged side by side in another direction (Y) perpendicular to one direction (X), and the first wiring is arranged along the direction (X). The array structure of the first wiring 43 and the second wiring 44 according to an embodiment of the present disclosure is not limited thereto.

[0180] Figure 4 is a perspective view of a portable electronic device including an ultrasonic sensor area, and Figure 5 is a cross-sectional view of the portable electronic device.

[0181] Referring to Figure 4 the portable electronic device PED may include a housing CS, a display device DIS, a sound output device SOM, an image sensor CAM, an illuminance sensor IS, a speaker SPK, a microphone MIC, a headphone port EP, and a charging port CP. The portable electronic device PED may include a covering member 200 exposed to the user 3, an ultrasonic sensor 100 provided on the rear surface of the covering member 200, an ultrasonic sensor controller 400, and a display device 300.

[0182] A portable electronic device PED may include a display area DA that overlaps with a display device DIS and a bezel area BA provided with an ultrasonic sensor area UA. When the ultrasonic sensor area UA is configured to detect a user's fingerprint, considering the size of the user's fingerprint, the ultrasonic sensor area UA may be adjusted to a wide rectangular shape that is 20 mm wide and 10 mm long, but the ultrasonic sensor area UA of the present disclosure is not limited thereto, and a non-limiting structure having various sizes such as circular, oval, and polygonal shapes may be applied.

[0183] Although the ultrasonic sensor area UA is illustrated as being formed in the bezel area BA on the front surface of the portable electronic device PED, the position of the ultrasonic sensor area UA is not limited thereto. For example, the ultrasonic sensor area UA may be provided at at least a part or the entire area of the display device DIS and at least a part or the entire area of a housing CS on the rear surface of the portable electronic device PED. Figure 4

[0184] Although the portable electronic device PED is illustrated as a smart phone, it is not limited thereto. For example, the portable electronic device according to an embodiment of the present disclosure may be a tablet or a notebook computer. In addition, the display device according to an embodiment of the present disclosure may be applied to various electronic devices such as a monitor (e.g., in a vehicle or other transportation means), a television (TV), and the portable electronic device PED.

[0185] The housing CS may be formed to cover one or more of the front surface, side surfaces, and rear surface of the portable electronic device PED. The housing CS may be formed of plastic. The display device DIS, a sound output device SOM, an image sensor CAM, and an illuminance sensor IS may be provided on the front surface of the housing CS. A microphone MIC, a headphone port EP, and a charging port CP may be provided at one side surface of the housing CS.

[0186] The display device DIS may occupy most of the front surface of the portable electronic device PED. A portion of the display device DIS that is not covered by the housing CS may overlap with the display area of the display device DIS, and the housing CS may overlap with the non-display area of the display device DIS.

[0187] The sound output device SOM can be a receiving device that outputs the voice of the other party during a call with the other party. The image sensor CAM is a device configured to capture an image seen in front of the portable electronic device PED, and another image sensor can be additionally provided at the rear surface of the portable electronic device PED. The illuminance sensor IS is a device configured to adjust the illuminance of the display device DIS by detecting the amount of incident light. The microphone MIC is a transmitting device configured to convert the sound wave of the user's voice into an electrical signal and transmit the converted electrical signal during a call with the other party. The speaker SPK outputs a sound signal related to the function or application executed by the portable electronic device PED. The headphone jack EP is a port configured to output the sound signal to the headphones instead of the speaker SPK when the headphones are inserted or accommodated. The charging port CP is a port that connects a charger configured to charge the battery of the portable electronic device PED.

[0188] Figure 5 is a cross-sectional view of a display device including an ultrasonic sensor according to an embodiment of the present disclosure.

[0189] Referring to Figure 5 , the portable electronic device PED according to an embodiment of the present disclosure may include a cover member 200, a display device 300, an ultrasonic sensor 100, and an ultrasonic sensor controller 400.

[0190] The cover member 200 may include any one of sapphire glass and Gorilla glass or a laminated structure thereof. A plastic substrate having a predetermined strength may also be used, but the embodiments of the present disclosure are not limited thereto. In addition, as previously Figure 4 shown, the body of the user 3 may be in contact with the upper surface of the cover member 200. Here, the body of the user 3 may be the fingerprint of the finger of the user 3 including identification information.

[0191] The display device 300 may be a display device that displays a predetermined image. For example, the display device 300 may include an organic light emitting diode (OLED), but the embodiments of the present disclosure are not limited thereto. For example, in addition to the organic light emitting display, the display device 300 may also be configured as a liquid crystal display or a quantum dot light emitting display.

[0192] The ultrasonic sensor 100 and the ultrasonic sensor controller 400 may be arranged to overlap with the ultrasonic sensor area UA of the bezel area BA. Refer to Figure 6 and Figure 7 for a description of the detailed configuration of the ultrasonic sensor 100 and the ultrasonic sensor controller 400.

[0193] Figure 6 and Figure 7 illustrate display devices according to an embodiment of the present disclosure and another embodiment.

[0194] Referring to Figure 6 , a display device according to an embodiment of the present disclosure may include a cover member 200, an ultrasonic sensor 100 disposed at a rear surface of the cover member 200, and an ultrasonic sensor controller 400.

[0195] The ultrasonic sensor 100 according to an embodiment of the present disclosure includes a piezoelectric member 140, an upper electrode 160 formed on an upper surface of the piezoelectric member 140, a substrate 110 configured to support the piezoelectric member 140, and a conductive adhesive member 130 disposed between the piezoelectric member 140 and the substrate 110.

[0196] The substrate 110 may be at least one of a metal substrate, a plastic substrate, and a glass substrate.

[0197] When a metal substrate is used as the substrate 110, the substrate may include at least one of a brass substrate and an aluminum substrate, but embodiments of the present disclosure are not limited thereto.

[0198] When a metal substrate is used as the substrate 110, the support member 180 to be described later may not be used, and the substrate 110 may simultaneously perform the functions of the substrate and the support member 180.

[0199] When a plastic substrate is used as the substrate 110, the substrate may be a polyimide substrate, but embodiments of the present disclosure are not limited thereto.

[0200] When a glass substrate is used as the substrate 110, the substrate may be indium tin oxide (ITO) glass, but embodiments of the present disclosure are not limited thereto.

[0201] A brass substrate may be used as the substrate 110 in the ultrasonic sensor 100 according to an embodiment of the present disclosure. When a brass substrate is used as the substrate 110, the substrate may be provided to have a thickness of about 1.0 mm and achieve ultrasonic transmission and reception functions without the configuration of the support member 180 described in Figure 7 .

[0202] In addition, the ultrasonic sensor 100 according to an embodiment of the present disclosure may be configured without a lower electrode. Thus, an electrical signal may be applied to the piezoelectric member 140 through a medium of the substrate 110 in contact with the first wiring 430.

[0203] The piezoelectric member 140 may be a film-type piezoelectric member including ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer. In the ultrasonic sensor 100 according to an embodiment of the present disclosure, the piezoelectric member 140 is not limited to the above materials, and materials that can convert electrical energy into mechanical energy through the piezoelectric phenomenon and the inverse piezoelectric phenomenon to generate ultrasonic waves having a predetermined frequency and convert mechanical energy into electrical energy can be used without limitation.

[0204] When transmitting ultrasonic waves by driving the ultrasonic sensor to be described later, the piezoelectric member 140 may output ultrasonic waves to the front or rear of the piezoelectric member 140. The ultrasonic waves output to the front of the piezoelectric member 140 may be output to the outside of the opposing substrate 190 through predetermined reflection, transmission, and absorption while passing through other components or media provided at the upper part of the piezoelectric member.

[0205] According to an embodiment of the present disclosure, the piezoelectric member 140 may be a film-type piezoelectric member that undergoes compression or stretching (or elongation) rotating in one direction.

[0206] The conductive adhesive member 130 may be provided between the substrate 110 and the piezoelectric member 140, may attach the substrate 110 and the piezoelectric member 140, and electrically connect the substrate 110 and the piezoelectric member 14. The conductive adhesive member 130 may include at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet (UV) adhesive, but the embodiments of the present disclosure are not limited thereto.

[0207] According to an embodiment of the present disclosure, the thickness of the conductive adhesive member 130 may be 5 μm or less. If the thickness of the conductive adhesive member 130 exceeds 5 μm, the ultrasonic transmission / reception efficiency may be reduced.

[0208] According to an embodiment of the present disclosure, the upper electrode 160 may be an electrode including silver (Ag). For example, when the upper electrode 160 includes silver (Ag) and is used as a solid metal, due to the damping effect of the ultrasonic characteristics of the ultrasonic sensor 100 caused by the difference in physical properties from the piezoelectric member 140, the ultrasonic waves may be attenuated or the intensity of the center frequency may be reduced. Therefore, the upper electrode 160 according to an embodiment of the present disclosure may be silver paste (Ag paste). For example, the silver paste may be silver paint or silver epoxy resin. Here, the silver paint or silver epoxy resin may be a material including both silver nanoparticles and a binder.

[0209] The silver nanoparticles may have a size of 200 nm or less. When the size of the silver nanoparticles is 200 nm or less, the ultrasonic sensor may have transmission and reception performance due to the increased surface area according to the refinement of the silver nanoparticles.

[0210] The silver paste may include 90 to 95 wt% of silver nanoparticles and 5 to 10 wt% of a binder. If the silver paste has less than 90 wt% of silver nanoparticles, there may be a problem of reduced conductivity of the electrode.

[0211] The upper electrode 160 can be prepared by performing a screen printing process or a spraying process on a solvent in which silver (Ag) paste is diluted, and the upper electrode 160 can be prepared as an ethanol-based solvent without using harmful organic solvents such as ketone-based solvents used in solution processes.

[0212] Here, the binder can be silver epoxy or silver paint. Since the upper electrode 160 according to an embodiment of the present disclosure includes silver and a binder, referring to Table 1 above, the acoustic impedance can be based on the mixing ratio of silver and the binder, and the difference from the piezoelectric member 140 located below the upper electrode 160 is reduced, thereby improving the transmission and reception performance of ultrasonic waves.

[0213] Therefore, when the upper electrode 160 includes silver (Ag) paste, the upper electrode 160 can finally be configured as a composite structure including silver (Ag) particles and a binder after undergoing the above-described solution-based coating and drying processes.

[0214] Alternatively, according to another embodiment of the present disclosure, the upper electrode 160 can be prepared by a screen printing process or a spraying process based on a solvent-free solvent.

[0215] If the upper electrode 160 uses a ketone-based solvent and the piezoelectric member 140 uses a film-type PVDF-based material, physical deformation of the piezoelectric member may occur during drying of the upper electrode, which may cause a problem that the adhesion force to the object to which the ultrasonic sensor is attached is weakened.

[0216] The thickness of the upper electrode 160 can be 10 μm or less.

[0217] If the thickness of the upper electrode 160 exceeds 10 μm, the ultrasonic attenuation effect of the upper electrode 160 will increase, and as a result, the transmission and reception performance of the ultrasonic sensor 100 may deteriorate.

[0218] In addition, if the thickness of the upper electrode 160 exceeds 10 μm, a corrugation phenomenon may occur in which it is divided into two bands in the part where the ultrasonic radiation energy is maximum in the frequency response, and as a result, the transmission and reception performance of the ultrasonic sensor 100 may deteriorate or decrease.

[0219] In addition, the surface roughness of the upper electrode 160 can be 0.01 μm or less. Here, the surface of the upper electrode 160 can be the upper surface facing the user 3.

[0220] According to an embodiment of the present disclosure, the upper electrode 160 may have a surface roughness of 0.01 μm or less and may be configured to have a flat surface. The ultrasonic sensor according to an embodiment of the present disclosure includes the upper electrode 160 having an upper surface with a low surface roughness, so that scattering in random directions occurring on the surface of the upper electrode 160 can be reduced. Therefore, since the ultrasonic sensor 100 according to an embodiment of the present disclosure includes the upper electrode 160 having a surface roughness of 0.01 μm or less, losses due to surface scattering of the upper electrode 160 can be reduced when receiving ultrasonic waves generated by the piezoelectric member 140 or ultrasonic waves reflected from the user 3.

[0221] According to an embodiment of the present disclosure, the ultrasonic sensor 100 may further include an ultrasonic sensor controller 400 configured to control the ultrasonic sensor 100.

[0222] The ultrasonic sensor controller 400 may include an ultrasonic sensor integrated circuit 410 and a flexible printed circuit 420, and may include a first wiring 430 and a second wiring 440 configured to apply signals to the ultrasonic sensor 100 through the flexible printed circuit 420.

[0223] The ultrasonic sensor integrated circuit 410 may be electrically connected to the ultrasonic sensor 1 to control the driving of the ultrasonic sensor 100 and read the fingerprint pattern of the user 3 identified by the ultrasonic sensor 100. The ultrasonic sensor integrated circuit 410 may be provided in the form of integrating a fingerprint sensor driving unit configured to drive the ultrasonic sensor 100 and a readout integrated circuit configured to read (or decode) user biometric information detected by the ultrasonic sensor 100 and output it as a digital value. The ultrasonic sensor integrated circuit 410 may be electrically connected to the ultrasonic sensor 100 to control the generation and reception of ultrasonic waves during a first operation period configured to generate ultrasonic waves and a second operation period configured to receive ultrasonic waves, and analyze the data of the received reflected ultrasonic waves to identify fingerprints.

[0224] The flexible printed circuit 420 may be electrically connected to the ultrasonic sensor integrated circuit 410 and the ultrasonic sensor 100, and the flexible printed circuit 402 may have a predetermined circuit pattern formed on the flexible printed circuit 420 and may be formed of a heat-resistant plastic including polyimide and polyester as flexible materials.

[0225] The first wiring 430 may be provided at the rear surface of the substrate 110 and may be provided to at least partially overlap the substrate 110. When the ultrasonic sensor 100 includes a plurality of pixels, it may include a plurality of first wirings 430 for independently driving each of the plurality of pixels.

[0226] The second wiring 440 may be disposed on the upper surface of the piezoelectric member 140 and may be electrically connected to the upper electrode 160. The second wiring 440 may include a plurality of second wirings 440 to independently drive each of the plurality of pixels when the ultrasonic sensor 100 includes a plurality of pixels.

[0227] According to an embodiment of the present disclosure, the first wiring 430 and the second wiring 440 may be formed of a copper tape having high conductivity, but the embodiments of the present disclosure are not limited thereto.

[0228] When sending ultrasonic waves by driving the ultrasonic sensor to be described later, the piezoelectric member 140 may output ultrasonic waves to the front or rear of the piezoelectric member 140. The ultrasonic waves output to the front of the piezoelectric member 140 may be output to the outside of the cover member 200 through predetermined reflection, transmission, and absorption while passing through other components or media disposed on the upper portion of the piezoelectric member.

[0229] Referring to Figure 7 , a display device including an ultrasonic sensor according to another embodiment of the present disclosure may include a cover member 200, an ultrasonic sensor 100 disposed on the rear surface of the cover member 200, and an ultrasonic sensor controller 400. Since only the configuration of the ultrasonic sensor 100 is changed in a display device including an ultrasonic sensor according to another embodiment of the present disclosure compared to the above-described Figure 6 embodiment of the present disclosure, the changed configuration will be mainly described below. Figure 7 In a display device including an ultrasonic sensor according to another embodiment of the present disclosure, only the configuration of the ultrasonic sensor 100 is changed, so the changed configuration will be mainly described below.

[0230] The ultrasonic sensor of a display device according to another embodiment of the present disclosure may include a substrate 110, a support member 180, conductive adhesive members 130a and 130b, a lower electrode 120, a piezoelectric member 140, an upper electrode 160, and, compared to the ultrasonic sensor 100 described in Figure 6 , may further include a lower electrode 120, a support member 180, a plurality of conductive adhesive members 130a and 130b, and a counter substrate 190. Therefore, repetitive descriptions may be omitted or briefly provided.

[0231] Here, the substrate 110 may be a plastic substrate. When a plastic substrate is used as the substrate 110, the substrate may be prepared as a polyimide substrate having a thickness of about 0.2 mm.

[0232] The lower electrode 120 may be prepared in the same manner as the upper electrode 160 described with reference to Figure 6 .

[0233] Therefore, when the lower electrode 120 includes silver (Ag), a silver (Ag) paste including silver (Ag) nanoparticles, a solvent, a binder, etc. can be prepared by a screen printing process or a spraying process, and the silver (Ag) paste can be prepared as an ethanol-based solvent so as not to use harmful organic solvents such as ketone-based solvents.

[0234] Therefore, when the lower electrode 120 includes the silver (Ag) paste, the lower electrode 120 can be finally configured as a composite structure including the silver (Ag) paste and a binder after undergoing the above solution-based coating and drying processes.

[0235] Alternatively, according to another embodiment of the present disclosure, the lower electrode 120 can be configured by a screen printing process or a spraying process based on a solvent-free one that does not include a binder.

[0236] The support member 180 can include a metal and can include at least one of brass and aluminum, but the embodiments of the present disclosure are not limited thereto.

[0237] For example, the support member 180 can be an aluminum plate of about 0.2 mm and can be prepared to have horizontal and vertical dimensions corresponding to those of the piezoelectric member 140.

[0238] In addition, when aluminum is used as the support member 180, a black anodizing treatment can be additionally performed on the support member 180. Here, the black anodizing can be colored black by anodizing.

[0239] According to another embodiment of the present disclosure, the ultrasonic sensor 100 can further include an ultrasonic sensor controller 400 configured to control the ultrasonic sensor 100.

[0240] The ultrasonic sensor controller 400 can include an ultrasonic sensor integrated circuit 410 and a flexible printed circuit 420, and can include a first wiring 430 and a second wiring 440 configured to apply signals to the ultrasonic sensor 100 through the flexible printed circuit 420.

[0241] Here, the first wiring 430 can be electrically connected to the lower electrode 120 through the second conductive adhesive member 130b, and the second wiring 440 can be arranged to surround the upper electrode 160. Therefore, the ultrasonic sensor 100 according to another embodiment of the present disclosure can have a structure in which the upper electrode 160 is exposed at the uppermost part.

[0242] An ultrasonic sensor according to another embodiment of the present disclosure may further include a counter substrate 190. The counter substrate 190 may be disposed on the upper electrode 160 and the second wiring 440, and may be prepared in a form in which a region corresponding to the region of the piezoelectric member 140 or the upper electrode 160 is open. Accordingly, a predetermined air layer may exist above the upper electrode 160. The counter substrate 190 may be adjusted to have the same thickness as the substrate 110, but the thickness of the counter substrate 190 is not limited to the same thickness as the substrate 110.

[0243] Figure 8A and Figure 8B are the results of measuring the surface roughness and thickness of the upper electrode according to an embodiment of the present disclosure. In Figure 8A and Figure 8B , the upper electrodes 16 and 160 are prepared by applying silver paste (Ag paste) to a PVDF film prepared to have a thickness of 24 μm using ethanol as a solvent and drying, and the surface roughness and thickness are measured using an atomic force microscope (AFM).

[0244] Referring to Figure 8A and Figure 8B , the thicknesses of the upper electrodes 16 and 160 are measured to be uniformly about 13 μm as a whole, and the surface roughness is measured to be about 0.0099 μm. Referring to Figure 8A and Figure 8B , it can be seen that the upper electrodes 16 and 160 according to an embodiment of the present disclosure can be uniformly prepared to have fewer surface defects and a low surface roughness value.

[0245] Figure 9A and Figure 9B are the results of measuring the surface roughness and thickness of the upper electrode according to the experimental example. In Figure 9A and Figure 9B , the upper electrode is prepared by attaching a copper tape to a PVDF film prepared to have a thickness of 24 μm using a conductive adhesive member, and the surface roughness and thickness are measured using an atomic force microscope (AFM).

[0246] Referring to Figure 9A and Figure 9B , it is measured that the upper electrode prepared using the copper tape and the conductive adhesive member has a thickness of about 38 μm, and the surface roughness is measured to be about 0.01 μm.

[0247] Figure 10A show the results of measuring the phase and impedance according to the frequency of the ultrasonic sensor according to an embodiment of the present disclosure. Figure 10B and Figure 10C show the results of measuring the impedance according to the presence or absence of a reflector above the ultrasonic sensor according to an embodiment of the present disclosure. Figures 10A to 10CThe measurement was performed using a commercial UTEX 340 pulse generator - receiver. A signal with a length of 2 ns (nanoseconds) was generated with an output voltage of 200 Vpp (V peak - to - peak) and applied to the ultrasonic sensor 1. The signal received after the reflector echo was amplified by 40 dB in the pulse generator - receiver to obtain the pulse - echo response and spectrum.

[0248] Referring to Figure 10A , it can be seen that the ultrasonic sensor according to an embodiment of the present disclosure has a high center frequency and a bandwidth of about 60 to 70 MHz.

[0249] Referring to Figure 10B and Figure 10C , in the ultrasonic sensor according to an embodiment of the present disclosure, it can be seen that ultrasonic waves from the reflector echo are observed. The received signal of the received ultrasonic wave is measured to have an intensity exceeding 6 dB.

[0250] Figure 11A is the result of measuring the phase and impedance according to frequency of an ultrasonic sensor according to another embodiment of the present disclosure. Figure 11B and Figure 11C are the results of measuring the impedance according to the presence or absence of a reflector above the ultrasonic sensor according to an embodiment of the present disclosure. The measurement of Figures 11A to 11C was performed using a commercial UTEX 340 pulse generator - receiver. A signal with a length of 2 ns (nanoseconds) was generated as a pulse voltage of 200 Vpp (V peak - to - peak) and applied to the ultrasonic sensor 1. The signal received after the reflector echo was amplified by 40 dB at the pulse generator - receiver.

[0251] Referring to Figure 11A , it can be seen that the ultrasonic sensor according to an embodiment of the present disclosure has a high center frequency and a bandwidth of about 60 to 70 MHz.

[0252] Referring to Figure 11B and Figure 11C , it can be seen that in the ultrasonic sensor according to an embodiment of the present disclosure, ultrasonic waves from the reflector echo are observed. The received signal of the received ultrasonic wave is measured to have an intensity exceeding 6 dB.

[0253] Figures 12 to 26 is a cross - sectional view of the ultrasonic sensor according to the experimental example.

[0254] Figure 12The ultrasonic sensor is prepared by forming a PVDF film having a width and length of 1 cm and a thickness of 28 μm as a piezoelectric member 14 on an indium tin oxide (ITO) glass substrate 11 having a width and length of 50 mm and a thickness of 1 mm, forming an upper electrode 16 and a lower electrode 12 on the upper and lower portions of the piezoelectric member, respectively, and forming an auxiliary member 5 including an insulating epoxy adhesive on one side of the piezoelectric member 14, the lower electrode 12, and the upper electrode 16 to be configured as a support structure. The lower electrode 12 and the upper electrode 16 have silver paste and are prepared to have a thickness of about 10 μm. In addition, in Figure 12 In the ultrasonic sensor, the first wiring 43 of the ultrasonic sensor controller 4 and the lower electrode 12 are electrically connected through the medium of the conductive adhesive member 13, and the conductive adhesive member 13 is prepared as a silicone-based adhesive applied to the front surface of the substrate. The conductive adhesive member 13 is prepared to have a thickness of about 5 μm. In addition, a second wiring 44 is provided to cover the entire upper electrode 16. Here, the first wiring 43 and the second wiring 44 are prepared as copper strips.

[0255] Figure 12 The ultrasonic sensor uses a commercial device UTEX 340 pulse generator-receiver to generate a signal with a frequency set to 1 wavelength of 5 MHz, a sound velocity of 340 m / s, and a voltage of 300 V, applies the signal to the ultrasonic sensor 1, and the received signal after being reflected by the reflector echo is amplified by 20 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum.

[0256] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 12 described, only the ultrasonic transmission waveform is measured, and the received signal reflected by the reflector is not observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 12 is measured to have a slightly lower intensity.

[0257] Compared with the ultrasonic sensor of Figure 12 , the ultrasonic sensor of Figure 13 has the same configuration except that the second wiring 44 is not set to cover the upper electrode 16 and is configured to only contact one side of the upper electrode 16. Therefore, the repeated description can be omitted or briefly provided.

[0258] Figure 13 The ultrasonic sensor uses a commercial device UTEX 340 pulse generator-receiver to generate a signal with a frequency set to 1 wavelength of 5 MHz, a sound velocity of 340 m / s, and a voltage of 300 V, applies the signal to the ultrasonic sensor 1, and the received signal after being reflected by the reflector echo is amplified by 20 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum.

[0259] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 13 described, only the ultrasonic transmission waveform was measured, and the received signal reflected by the reflector was not observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 13 was measured to be lower than that of the ultrasonic sensor prepared by Figure 12

[0260] Figure 14 The ultrasonic sensor of Figure 12 has the same structure as the ultrasonic sensor of Figure 12 , except that the conductive bonding member 13 is changed to a conductive epoxy adhesive. Therefore, the repeated description can be omitted or provided briefly.

[0261] Figure 14 The ultrasonic sensor of Figure 14 uses a commercial device UTEX 340 pulse generator-receiver to generate a signal with a frequency set to 1 wavelength at 5 MHz, a sound velocity of 340 m / s, and a voltage of 300 V, and applies the signal to the ultrasonic sensor 1, and the signal received after the reflector echo is amplified by 20 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum.

[0262] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 14 described, only the ultrasonic transmission waveform was measured, and the received signal reflected by the reflector was not observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 12 is similar to that of the ultrasonic sensor prepared by Figure 14

[0263] Figure 15 The ultrasonic sensor of Figure 13 has the same structure as the ultrasonic sensor of Figure 13 , except that the conductive bonding member 13 is changed to a conductive epoxy adhesive. Therefore, the repeated description can be omitted or provided briefly.

[0264] Figure 15 The ultrasonic sensor of Figure 15 uses a commercial device UTEX 340 pulse generator-receiver to generate a signal with a frequency set to 1 wavelength at 5 MHz, a sound velocity of 340 m / s, and a voltage of 300 V, and applies the signal to the ultrasonic sensor 1, and the signal received after the reflector echo is amplified by 20 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum.

[0265] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 15 described, only the ultrasonic transmission waveform was measured, and the received signal reflected by the reflector was not observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 15The ultrasonic transmission intensity of the fabricated ultrasonic sensor is measured to be lower than that of the ultrasonic sensor fabricated by Figure 12 The ultrasonic sensor fabricated by

[0266] Figure 16 The ultrasonic sensor of Figure 16 is fabricated by forming a PVDF film with a width and length of 1 cm and a thickness of 28 μm as a piezoelectric member 14 on an indium tin oxide (ITO) glass substrate 11 with a width and length of 50 mm and a thickness of 1 mm, forming an upper electrode 16 including silver paste on the upper part of the piezoelectric member, and forming an auxiliary member 5 including an insulating epoxy adhesive to surround the side surfaces of the upper electrode 16 and the piezoelectric member 14. The upper electrode 16 is fabricated to have a thickness of about 10 μm. In Figure 16 In the ultrasonic sensor of Figure 16 , the first wiring 43 and the piezoelectric member 14 are dielectrically connected through a conductive adhesive member 13, and the conductive adhesive member 13 is fabricated as a conductive epoxy adhesive applied to the front surface of the substrate. The conductive adhesive member 13 is fabricated to have a thickness of about 5 μm. In addition, a second wiring 44 is provided to cover the entire upper electrode 16. Here, the first wiring 43 and the second wiring 44 are fabricated as copper tapes.

[0267] Figure 16 The ultrasonic sensor of Figure 16 uses a commercial equipment UTEX 340 pulse generator - receiver to generate a signal with a frequency set to 1 wavelength of 5 MHz, a sound speed of 340 m / s, and a voltage of 300 V, applies the signal to the ultrasonic sensor 1, and the received signal after being reflected by the reflector echo is amplified by 20 dB in the pulse generator - receiver to obtain a pulse - echo response and a spectrum.

[0268] As Figure 27 shown, in the ultrasonic sensor fabricated as Figure 16 In the ultrasonic sensor fabricated as Figure 16 , only the ultrasonic transmission waveform is measured, and no received signal reflected by the reflector is observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor fabricated by Figure 16 is measured to be lower than that of the ultrasonic sensor fabricated by Figure 12 The ultrasonic sensor fabricated by

[0269] In Figure 17 In the ultrasonic sensor of Figure 17 , a PVDF film with a width and length of 50 mm and a thickness of 28 μm is formed as a piezoelectric member 14 on a brass substrate 11 with a width and length of 50 mm and a thickness of 1 mm, and the electrodes above and below the piezoelectric member are omitted. A conductive adhesive member 13 formed of a silicone - based adhesive with a thickness of 5 μm is formed between the substrate 11 and the piezoelectric member 14. The second wiring 44 of the ultrasonic sensor controller 4 is fabricated to contact a part of the piezoelectric member 14, and the first wiring 43 is fabricated to contact at least a part of the substrate 11.

[0270] Figure 17 The ultrasonic sensor uses a commercial UTEX 340 pulse generator - receiver to generate a signal with a frequency set to 5 MHz, one wavelength, a sound velocity of 340 m / s, and a voltage of 300 V, and applies the signal to the ultrasonic sensor 1. The signal received after being reflected by the reflector echo is amplified by 20 dB in the pulse generator - receiver to obtain a pulse - echo response and spectrum.

[0271] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 17 such, only the ultrasonic transmission waveform is measured, and the received signal reflected by the reflector is not observed. The ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 17 is measured to be higher than that of the ultrasonic sensor prepared by Figure 12 such.

[0272] Compared with the ultrasonic sensor of Figure 17 such, the ultrasonic sensor of Figure 18 is prepared to have the same structure as Figure 17 such, except that the position of the first wiring is changed to contact the lower surface of the piezoelectric member 14, the upper electrode 16 is formed on the piezoelectric member, and the upper electrode 16 is configured to contact the second wiring. Therefore, the repeated description can be omitted or provided briefly. Figure 18 The upper electrode of

[0273] Figure 18 such uses silver paste and is prepared to have a thickness of about 10 μm.

[0274] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 18 such, only the ultrasonic transmission waveform is measured, and the received signal reflected by the reflector is not observed. The ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 18 is measured to have a high intensity compared with the ultrasonic sensor prepared by Figure 12 such.

[0275] In Figure 19In the ultrasonic sensor, a PVDF film having a width and length of 50 mm and a thickness of 28 μm is formed as a piezoelectric member 14 on a brass substrate 11 having a width and length of 1 cm and a thickness of 1 mm, and the electrodes above and below the piezoelectric member are omitted. A conductive adhesive member 13 including an acrylic-based ultraviolet (UV) adhesive with a thickness of 5 μm is formed between the substrate 11 and the piezoelectric member 14. The second wiring 44 of the ultrasonic sensor controller 4 is prepared to cover the upper surface of the piezoelectric member 14, and the first wiring 43 is prepared to contact at least a part of the substrate 11.

[0276] As Figure 19 for the ultrasonic sensor, using a commercial equipment UTEX 340 pulse generator-receiver, a signal having a length of 2 ns (nanoseconds) is generated to have an output voltage of 200 Vpp and is applied to the ultrasonic sensor 1, and the signal received after the reflector echo is amplified 40 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum, the results of which are as Figure 28 and Figure 29 shown.

[0277] It can be seen that, as Figure 19 prepared, the ultrasonic sensor has a high center frequency and a bandwidth of about 60 to 70 MHz, as Figure 28 shown.

[0278] In addition, in the ultrasonic sensor prepared as Figure 19 such, the pulse generator-receiver measurement waveforms are observed under various conditions, such as oscillation in air, oscillation in air after applying gel, and oscillation in air after adding a reflector and applying gel, as Figure 29 shown, but no received signal of the reflector echo is observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 19 such is measured to be lower compared with the ultrasonic sensor prepared by Figure 12 such.

[0279] Compared with Figure 17 the ultrasonic sensor of Figure 20 such, the ultrasonic sensor of Figure 17 such is prepared to have the same structure as

[0280] Figure 20The ultrasonic sensor uses a commercial UTEX 340 pulse generator-receiver to generate a signal with a frequency set to 5 MHz, a wavelength of 1, a sound velocity of 340 m / s, and a voltage of 300 V, and applies the signal to the ultrasonic sensor 1. The signal received after being reflected by the reflector echo is amplified by 20 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum.

[0281] As Figure 27 shown, in the ultrasonic sensor prepared as Figure 20 described, only the ultrasonic wave transmission waveform was measured, and the received signal reflected by the reflector was not observed. The ultrasonic transmission intensity of the ultrasonic sensor prepared by Figure 20 was measured to be higher than that of the ultrasonic sensor prepared by Figure 12 described.

[0282] In Figure 21 the ultrasonic sensor, a PVDF film with a width and length of 20 mm and a thickness of 20 μm is formed as the piezoelectric member 14 on a polyimide substrate 11 with a width and length of 25 mm and a thickness of 50 μm. The electrodes above and below the piezoelectric member 14 are omitted, and the first wiring 43 and the second wiring 44 are each configured to contact at least a part of the lower surface and the upper surface of the piezoelectric member 14. Thereafter, a paper with a width and length of 20 mm and a thickness of 2 mm is added as the support member 18' between the piezoelectric member, the first wiring, and the substrate 11, and conductive adhesive members 13a and 13b are formed as silicone-based adhesives with a thickness of 10 μm on both sides of the support member 18'. In addition, an opposing substrate 19 is prepared on the piezoelectric member 14 and the second wiring 44. The opposing substrate 19 has the same size as the substrate 11 but has an opening with a size corresponding to the piezoelectric member 14. Here, the piezoelectric member 14 and the support member 18' can be arranged at the center of the substrate 11.

[0283] Figure 22 The ultrasonic sensor of Figure 21 is prepared to have the same configuration as the ultrasonic sensor of

[0284] Figure 23 except that the support member 18 is changed to an aluminum plate. Therefore, the repeated description can be omitted or provided briefly. Figure 21 The ultrasonic sensor of

[0285] Figure 24 is prepared to have the same configuration as the ultrasonic sensor of Figure 21The ultrasonic sensor has the same configuration, except that the first conductive adhesive member 13a, the support member 18 formed of an aluminum plate, the second conductive adhesive member 13b, the support member 18' formed of paper, and the third conductive adhesive member 13c are arranged in sequence between the substrate 11 and the first wiring 43. The structure on the first wiring can be substantially the same. Therefore, repetitive descriptions can be omitted or provided briefly.

[0286] Figures 21 to 24 The ultrasonic sensor uses a commercial device UTEX 340 pulse generator - receiver to generate a signal with a frequency set to 1 wavelength at 5 MHz, a sound speed of 340 m / s, and a voltage of 300 V, and applies the signal to the ultrasonic sensor 1. The signal received after the reflector echo is amplified by 20 dB in the pulse generator - receiver to obtain a pulse - echo response and spectrum.

[0287] As Figure 27 shown, in the ultrasonic sensor prepared as Figures 21 to 24 described, only the ultrasonic wave transmission waveform was measured, and no received signal reflected by the reflector was observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor prepared by Figures 21 to 24 was measured to be lower in intensity compared to the ultrasonic sensor prepared by Figure 12 described.

[0288] Figure 25 The ultrasonic sensor of Figure 22 was prepared to have the same configuration as the ultrasonic sensor of

[0289] except that the support member 18 was changed to brass. Therefore, repetitive descriptions can be omitted or provided briefly. Figure 25 As the ultrasonic sensor of Figure 29 and Figure 30 shown, using a commercial device UTEX 340 pulse generator - receiver, a signal with a length of 2 ns (nanoseconds) is generated with an output voltage of 200 Vpp and applied to the ultrasonic sensor 1. The signal received after the reflector echo is amplified by 40 dB in the pulse generator - receiver to obtain a pulse - echo response and spectrum, the results of which are as

[0290] It can be seen that the ultrasonic sensor prepared as Figure 25 described has a high center frequency and a bandwidth of approximately 60 to 70 MHz, as Figure 30 shown.

[0291] In addition, in the case of Figure 25In the fabricated ultrasonic sensor, pulse generator-receiver measurement waveforms were observed under various conditions, such as oscillations in air, oscillations in air after applying gel, and oscillations in air after adding a reflector and applying gel, as Figure 29 shown, but no received signal of the reflector echo was observed. In addition, the ultrasonic transmission intensity of the ultrasonic sensor fabricated by Figure 25 was measured to be lower compared to the ultrasonic sensor fabricated by Figure 12 .

[0292] Figure 26 The ultrasonic sensor of was fabricated to have the same configuration as the ultrasonic sensor of Figure 23 , except that the upper electrode 16 was additionally disposed on the piezoelectric member 14. Therefore, repeated descriptions can be omitted or provided briefly.

[0293] As the Figure 26 ultrasonic sensor, using a commercial equipment UTEX 340 pulse generator-receiver, a signal with a length of 2 ns (nanoseconds) was generated with an output voltage of 200 Vpp and applied to the ultrasonic sensor 1, and the signal received after the reflector echo was amplified 40 dB in the pulse generator-receiver to obtain a pulse echo response and a spectrum, the results of which are as Figure 31 shown. It can be seen that the ultrasonic sensor fabricated as Figure 26 has a high center frequency and a broadband width of about 60 to 70 MHz, as Figure 31 shown.

[0294] As Figure 27 shown, in the ultrasonic sensor fabricated as Figure 26 , only the ultrasonic transmission waveform was measured, and no received signal reflected by the reflector was observed. The ultrasonic transmission intensity of the ultrasonic sensor fabricated by Figure 26 was measured to have a lower intensity compared to the ultrasonic sensor fabricated by Figure 12 .

[0295] Figures 32A to 32E An example of a method for manufacturing an ultrasonic sensor according to another embodiment of the present disclosure is illustrated.

[0296] First, referring to Figure 32A , the lower electrode 12 is patterned on the substrate 11, and the first wiring 43 of the ultrasonic sensor controller is connected to at least one side of the lower electrode 12. Additionally, a support member 18 may be disposed between the substrate 11 and the lower electrode 12, and at least a portion of the first wiring 43 may be disposed to overlap the lower electrode 12.

[0297] Here, the substrate 11 may be a plastic substrate. When the plastic substrate is used as the substrate 11, the substrate may be prepared as a polyimide substrate having a thickness of about 0.2 mm.

[0298] The support member 18 may be an aluminum plate having a thickness of about 0.2 mm, and the piezoelectric member 14 may be arranged to have dimensions corresponding to the substrate 11 or arranged to correspond only to each of the plurality of piezoelectric members 14.

[0299] The lower electrode 12 may be provided on the substrate 11 and may also be provided on the support member 18.

[0300] When the lower electrode 12 includes silver (Ag), a silver (Ag) paste including silver (Ag) nanoparticles, a solvent, a binder, etc. may be prepared by a screen printing process or a spraying process, and the silver (Ag) paste may be prepared as an ethanol-based solvent so as not to use harmful organic solvents such as ketone solvents.

[0301] Therefore, when the lower electrode 12 includes the silver (Ag) paste, the lower electrode 12 may finally be configured as a composite structure including the silver (Ag) paste and the binder after undergoing the above-described solution-based coating and drying processes.

[0302] The lower electrode 12 may be configured by a screen printing process or a spraying process based on a solvent-free one that does not include a binder. As Figure 32A shown, it may be patterned to correspond to a predetermined area. Here, the predetermined area may be an area where the piezoelectric member 14 described with reference to Figure 32B is provided. For example, the predetermined area may be a unit pixel area of the ultrasonic sensor.

[0303] The lower electrode 12 may be adjusted to have a predetermined horizontal and vertical width W and may be formed in a rectangular or square shape. In Figure 32A an example, a square having the same horizontal and vertical width is illustrated. For example, the horizontal and vertical width of the lower electrode 12 may be 20 μm, but the embodiments of the present disclosure are not limited thereto. In addition, the lower electrode 12 may be formed to be spaced apart from another adjacent lower electrode 12 by a predetermined distance D. For example, the distance D between the lower electrode 12 and another adjacent lower electrode 12 may be 10 μm, but the embodiments of the present disclosure are not limited thereto. Here, the described width W of the lower electrode 12 and the distance D between the lower electrode 12 and another adjacent lower electrode 12 may be equivalently applied to each of the width W of the piezoelectric member 14 and the upper electrode 16. The numerical values of the dimensions and intervals of the lower electrode 12, the piezoelectric member 14, and the upper electrode 16 of the ultrasonic sensor according to the embodiments of the present disclosure are not limited to the above description.

[0304] Therefore, the lower electrode 12 can be patterned after being prepared by performing the above-described screen printing process or spraying process. Alternatively, the lower electrode 12 can be prepared to be formed only in a predetermined region using a predetermined mask pattern.

[0305] The first wiring 43 can be in contact with at least one side of the lower electrode 12 or can be arranged to at least partially overlap the lower electrode 12. The first wiring 43 can be formed of a copper tape having high electrical conductivity, but the embodiments of the present disclosure are not limited thereto.

[0306] Next, referring to Figure 32B , the piezoelectric member 14 can be disposed on the lower electrode 12, and its size corresponds to that of the lower electrode 12. Here, the corresponding size can include the same size as the lower electrode 12, a size smaller than the lower electrode 12, and a size larger than the lower electrode 12, and the piezoelectric member 14 can be a size that does not affect the driving of the ultrasonic sensor in the unit pixel region of the adjacent ultrasonic sensor.

[0307] The piezoelectric member 14 can be a film-type piezoelectric member 14 including ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer. In the ultrasonic sensor 1 according to an embodiment of the present disclosure, the piezoelectric member 14 is not limited to the above materials, and materials that can convert electrical energy into mechanical energy through the piezoelectric phenomenon and the inverse piezoelectric phenomenon to generate ultrasonic waves having a predetermined frequency and convert mechanical energy into electrical energy can be used without limitation.

[0308] According to an embodiment of the present disclosure, the piezoelectric member 14 can be a film-type piezoelectric member that undergoes compression or stretching (or elongation) rotating in one direction, and according to an embodiment of the present disclosure, the piezoelectric member 14 can have a thickness of 10 to 50 μm.

[0309] The piezoelectric member 14 can be adjusted to have a predetermined horizontal and vertical width W and can be formed in a rectangular or square shape. In addition, the piezoelectric member 14 can be formed to be spaced apart from another adjacent piezoelectric member 14 by a predetermined distance D. Here, the description of the lower electrode 12 can be equally applied to the width W of the piezoelectric member 14 and the predetermined distance D between the piezoelectric member 14 and another adjacent piezoelectric member 14.

[0310] Therefore, the piezoelectric member 14 can be prepared by patterning a film-like piezoelectric member to correspond to a predetermined region. Additionally, if necessary, an adhesive member can be provided between the piezoelectric member 14 and the lower electrode 12.

[0311] Figure 32C An ultrasonic sensor in a state manufactured by Figure 32B is illustrated. Referring to Figure 32C, the support member 18, the lower electrode 12, and the piezoelectric member 14 may be sequentially disposed on the substrate 11. When the first wiring 43 is disposed below the lower electrode 12, the first conductive adhesive member 13a may be disposed below the first wiring 43, and the second conductive adhesive member 13b may be disposed on the first wiring 43. Accordingly, the first wiring 43 may be electrically connected to the lower electrode 12 through the second conductive adhesive member 13b.

[0312] The first conductive adhesive member 13a and the second conductive adhesive member 13b may include at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet (UV) adhesive, but embodiments of the present disclosure are not limited thereto. According to an embodiment of the present disclosure, the thicknesses of the first conductive adhesive member 13a and the second conductive adhesive member 13b may be 5 μm or less. When the thicknesses of the first conductive adhesive member 13a and the second conductive adhesive member 13b exceed 5 μm, the ultrasonic transmission / reception efficiency may be reduced.

[0313] Next, referring to Figure 32D , the upper electrode 16 may be formed on the piezoelectric member 14 to have corresponding dimensions. For example, the upper electrode 16 may be patterned to have corresponding dimensions on the piezoelectric member 14.

[0314] The upper electrode 16 may be disposed on the piezoelectric member 14 in dimensions corresponding to those of the piezoelectric member 14. Here, the corresponding dimensions may include dimensions identical to those of the piezoelectric member 14, dimensions smaller than those of the piezoelectric member 14, and dimensions larger than those of the piezoelectric member 14, and it may be a dimension that does not affect the driving of the unit pixel region of an adjacent ultrasonic sensor. Referring to Figure 32E , it can be seen that the dimensions of the upper electrode 16 are slightly smaller than those of the piezoelectric member 14.

[0315] The upper electrode 16 may be adjusted to have a predetermined horizontal and vertical width W and may be formed in a rectangular or square shape. In addition, the upper electrode 16 may be formed to be spaced apart from another adjacent upper electrode 16 by a predetermined distance D. Here, the description of the upper electrode 16 may be equally applicable to the width W of the upper electrode 16 and the predetermined distance D between the upper electrode 16 and another adjacent upper electrode 16.

[0316] Accordingly, the upper electrode 16 may be prepared by performing the screen printing process or the spraying process as described above and then patterning. Alternatively, the upper electrode 16 may be prepared only in a predetermined region using a predetermined mask pattern.

[0317] The upper electrode 16 may be an electrode including silver (Ag). For example, when the upper electrode 16 is used as a solid metal including silver (Ag), the ultrasonic wave may be attenuated or the intensity of the center frequency may be reduced due to the damping effect of the ultrasonic characteristics of the ultrasonic sensor caused by the difference in physical properties from the piezoelectric member 14. Therefore, the upper electrode 16 according to an embodiment of the present disclosure may be a silver paste (Ag paste). For example, the silver paste may be a silver paint or a silver epoxy resin. Here, the silver paint or the silver epoxy resin may be a material including both silver nanoparticles and a binder.

[0318] The silver nanoparticles may have a size of 200 nm or less. When the size of the silver nanoparticles is 200 nm or less, the ultrasonic sensor may have transmission and reception performance due to an increase in surface area according to refinement of the silver nanoparticles.

[0319] The silver paste may include 90 to 95 wt % of silver nanoparticles and 5 to 10 wt % of a binder. If the silver paste has less than 90 wt % of silver nanoparticles, there may be a problem of reduced conductivity of an electrode.

[0320] The upper electrode 16 may be prepared by performing a screen printing process or a spray coating process on a solvent in which a silver (Ag) paste is diluted, and may be prepared as an ethanol-based solvent so as not to use a harmful organic solvent such as a ketone-based solvent used in a solution process.

[0321] Figure 32E Illustrated in the Figure 32D Ultrasonic sensor in the state of manufacture. Figure 32E The second wiring 44 may be disposed at the upper surface of the piezoelectric member 14 and may be disposed to surround the upper electrode 16 so as to be electrically connected to the upper electrode 16. The second wiring 44 may be formed of a copper tape having high electrical conductivity, but the embodiments of the present disclosure are not limited thereto.

[0322] Next, if Figure 1 and Figure 2 As shown in the ultrasonic sensor according to the embodiment of the present disclosure and other embodiments, Figure 32E The manufactured ultrasonic sensor may also include a pressure plate 2 and an ultrasonic sensor controller 4 to operate as an independent ultrasonic sensor 1 and may be installed at a portable electronic device PED, such as Figure 4 and Figure 5 As shown, the driving is performed using an ultrasonic sensor for detecting identification information of the user 3 .

[0323] According to an embodiment of the present disclosure, in an ultrasonic sensor and a display device including the same, a piezoelectric member and an upper electrode are stable in structure and process.

[0324] In addition, according to an embodiment of the present disclosure, a structure and a display device including the structure may be provided, in which the ultrasonic transmission and reception sensitivities of an ultrasonic sensor are improved.

[0325] The ultrasonic sensor and the display device according to an embodiment of the present disclosure may be described as follows.

[0326] The ultrasonic sensor according to an embodiment of the present disclosure may include a substrate, a piezoelectric member disposed on the substrate, and an upper electrode disposed on the piezoelectric member, and the upper electrode may include silver paste.

[0327] According to some embodiments of the present disclosure, the substrate may be electrically connected to the rear surface of the piezoelectric member.

[0328] According to some embodiments of the present disclosure, the ultrasonic sensor may be configured to generate ultrasonic waves and receive the reflected ultrasonic waves.

[0329] According to some embodiments of the present disclosure, the silver paste may include silver epoxy resin or silver paint.

[0330] According to some embodiments of the present disclosure, the silver paste may include silver nanoparticles and a resin binder.

[0331] According to some embodiments of the present disclosure, the silver paste may include 90 to 95 wt% of silver nanoparticles and 5 to 10 wt% of a resin binder.

[0332] According to some embodiments of the present disclosure, the silver nanoparticles may have a size of 200 nm or less.

[0333] According to some embodiments of the present disclosure, the upper electrode may be formed using silver paste and an alcohol solvent.

[0334] According to some embodiments of the present disclosure, the surface roughness of the upper electrode may be 0.01 μm or less.

[0335] According to some embodiments of the present disclosure, the thickness of the upper electrode may be 10 μm or less.

[0336] According to some embodiments of the present disclosure, the piezoelectric member may include polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

[0337] According to some embodiments of the present disclosure, the substrate may be a metal substrate, and the metal substrate may be a brass substrate or an aluminum substrate.

[0338] According to some embodiments of the present disclosure, the ultrasonic sensor may further include a conductive adhesive member disposed between the substrate and the piezoelectric member, and the conductive adhesive member may include at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

[0339] According to some embodiments of the present disclosure, the thickness of the conductive adhesive member may be 5 μm or less.

[0340] According to some embodiments of the present disclosure, the ultrasonic sensor may further include an ultrasonic sensor controller disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor, and the ultrasonic sensor controller includes: a flexible printed circuit; an ultrasonic sensor integrated circuit mounted on one side of the flexible printed circuit; and a first wiring and a second wiring mounted on the other side of the flexible printed circuit and electrically connected to one surface and the other surface of the ultrasonic sensor.

[0341] According to some embodiments of the present disclosure, the first wiring may contact at least a portion of the rear surface of the substrate, and the second wiring may contact at least a portion of the rear surface of the upper electrode.

[0342] According to some embodiments of the present disclosure, the second wiring may be disposed to surround the upper electrode.

[0343] According to some embodiments of the present disclosure, the upper electrode may be exposed at the uppermost portion of the upper electrode.

[0344] A display device according to some embodiments of the present disclosure may include: a substrate; a piezoelectric member disposed on the substrate; a lower electrode disposed below the piezoelectric member; an upper electrode disposed to face the lower electrode and disposed on the piezoelectric member; and a support member disposed between the substrate and the lower electrode, wherein the upper electrode and the lower electrode include silver paste.

[0345] According to some embodiments of the present disclosure, the ultrasonic sensor may include a plurality of pixels, and each of the plurality of pixels may include a piezoelectric member, a lower electrode, and an upper electrode.

[0346] According to some embodiments of the present disclosure, each of the piezoelectric member, the lower electrode, and the upper electrode in each of the plurality of pixels may be spaced apart from each other by a predetermined distance.

[0347] According to some embodiments of the present disclosure, the silver paste may include silver nanoparticles and a binder.

[0348] According to some embodiments of the present disclosure, the silver paste may include 90 to 95 wt% of silver nanoparticles and 5 to 10 wt% of a binder.

[0349] According to some embodiments of the present disclosure, the silver nanoparticles may have a size of 200 nm or less.

[0350] According to some embodiments of the present disclosure, the upper electrode and the lower electrode may be formed using a silver paste and an ethanol-based solvent.

[0351] According to some embodiments of the present disclosure, the piezoelectric member may include polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

[0352] According to some embodiments of the present disclosure, the substrate may be a plastic substrate.

[0353] According to some embodiments of the present disclosure, the support member may include brass or aluminum.

[0354] According to some embodiments of the present disclosure, the display device may further include a conductive adhesive member disposed between the substrate and the piezoelectric member, the conductive adhesive member including at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

[0355] According to some embodiments of the present disclosure, the conductive adhesive member may include a first conductive adhesive member disposed to contact the support member and a second conductive adhesive member disposed to contact the lower electrode.

[0356] According to some embodiments of the present disclosure, the display device may further include an ultrasonic sensor controller disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor, the ultrasonic sensor controller including a flexible printed circuit, an ultrasonic sensor integrated circuit mounted on one side of the flexible printed circuit, and first and second wirings mounted on the other side of the flexible printed circuit and electrically connected to the surface of the ultrasonic sensor.

[0357] According to some embodiments of the present disclosure, the first wiring may be disposed between the substrate and the lower electrode, and the second wiring may contact at least a portion of the side surface of the upper electrode.

[0358] A display device according to some embodiments of the present disclosure includes: a cover member including a display area and an ultrasonic sensor area; a display device disposed on a rear surface of the cover member and overlapping the display area; and an ultrasonic sensor disposed on the rear surface of the cover member and overlapping the ultrasonic sensor area.

[0359] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the technical concept or scope of the present disclosure. Accordingly, embodiments of the present disclosure are intended to cover modifications and variations of the present disclosure as long as they fall within the scope of the appended claims and their equivalents.

[0360] Cross-reference to related applications

[0361] This application claims the benefit of priority of Korean Patent Application No. 10-2020-0139650, filed on Oct. 26, 2020, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference in its entirety as if fully set forth herein.

Claims

1. An ultrasonic sensor, the ultrasonic sensor comprising: A substrate; A piezoelectric member, the piezoelectric member being disposed at the substrate; An upper electrode, the upper electrode being disposed on the piezoelectric member; A pressing plate, the pressing plate being disposed on the piezoelectric member and configured to receive a fingerprint of a user; A first wiring and a second wiring, wherein the second wiring is disposed to surround the upper electrode in a plan view; An opposing substrate, the opposing substrate being disposed between the pressing plate and the upper electrode; and An air layer, the air layer being disposed between the pressing plate and the upper electrode, wherein the air layer is surrounded by the pressing plate, the opposing substrate, and the upper electrode, wherein the opposing substrate is prepared in a form with an open area corresponding to an area of the piezoelectric member, and the air layer is configured on an upper portion of the upper electrode, wherein the upper electrode includes silver paste, wherein the upper electrode has a flat surface facing the pressing plate.

2. The ultrasonic sensor according to claim 1, wherein, The substrate is electrically connected to a rear surface of the piezoelectric member.

3. The ultrasonic sensor according to claim 1, wherein, The ultrasonic sensor is configured to generate ultrasonic waves and receive reflected ultrasonic waves.

4. The ultrasonic sensor according to claim 1, wherein, The silver paste includes silver epoxy resin or silver paint.

5. The ultrasonic sensor according to claim 1, wherein, The silver paste includes silver nanoparticles and a resin binder.

6. The ultrasonic sensor according to claim 5, wherein, The silver paste includes 90 to 95 wt% of the silver nanoparticles and 5 to 10 wt% of the resin binder.

7. The ultrasonic sensor according to claim 5, wherein, The size of the silver nanoparticles ≤ 200 nm.

8. The ultrasonic sensor according to claim 1, wherein, The upper electrode is formed using the silver paste and an alcohol solvent.

9. The ultrasonic sensor according to claim 1, wherein, The surface roughness of the upper electrode ≤ 0.01 μm.

10. The ultrasonic sensor according to claim 1, wherein, The thickness of the upper electrode ≤ 10 μm.

11. The ultrasonic sensor according to claim 1, wherein, The piezoelectric member includes polyvinylidene fluoride PVDF or polyvinylidene fluoride-trifluoroethylene PVDF-TrFE.

12. The ultrasonic sensor according to claim 1, wherein, The substrate is a metal substrate, and the metal substrate is a brass substrate or an aluminum substrate.

13. The ultrasonic sensor according to claim 1, the ultrasonic sensor further comprising: A conductive adhesive member, the conductive adhesive member being disposed between the substrate and the piezoelectric member, wherein the conductive adhesive member includes at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

14. The ultrasonic sensor according to claim 13, wherein, The thickness of the conductive adhesive member ≤ 5 μm.

15. The ultrasonic sensor according to claim 1, the ultrasonic sensor further comprising: An ultrasonic sensor controller, the ultrasonic sensor controller being disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor, wherein the ultrasonic sensor controller includes: A flexible printed circuit; An ultrasonic sensor integrated circuit, the ultrasonic sensor integrated circuit being mounted on one side of the flexible printed circuit; and The first wiring and the second wiring, the first wiring and the second wiring being mounted on the other side of the flexible printed circuit and electrically connected to one surface and another surface of the ultrasonic sensor.

16. The ultrasonic sensor according to claim 15, wherein, The first wiring contacts at least a part of a rear surface of the substrate, and the second wiring contacts at least a part of a side surface of the upper electrode.

17. The ultrasonic sensor according to claim 16, wherein, The upper electrode is exposed at a topmost portion of the upper electrode.

18. An ultrasonic sensor, the ultrasonic sensor comprising: A piezoelectric member disposed on a substrate; A lower electrode disposed under the piezoelectric member; An upper electrode disposed to face the lower electrode and disposed on the piezoelectric member; A support member disposed between the substrate and the lower electrode; A pressing plate disposed on the piezoelectric member and configured to receive a user's fingerprint; A first wiring and a second wiring, wherein the second wiring is disposed to surround the upper electrode in a plan view; An opposing substrate disposed between the pressing plate and the upper electrode; and An air layer disposed between the pressing plate and the upper electrode, wherein the air layer is surrounded by the pressing plate, the opposing substrate, and the upper electrode, wherein the opposing substrate is prepared in a form with an open region corresponding to the region of the piezoelectric member, and the air layer is configured on the upper part of the upper electrode, wherein the upper electrode and the lower electrode include silver paste, wherein the upper electrode has a flat surface facing the pressing plate.

19. The ultrasonic sensor according to claim 18, wherein, The ultrasonic sensor includes a plurality of pixels, and each of the plurality of pixels includes the piezoelectric member, the lower electrode, and the upper electrode.

20. The ultrasonic sensor according to claim 19, wherein, In each of the plurality of pixels, the piezoelectric member, the lower electrode, and the upper electrode are spaced apart from each other by a predetermined distance.

21. The ultrasonic sensor according to claim 18, wherein, The silver paste includes silver nanoparticles and a binder.

22. The ultrasonic sensor according to claim 21, wherein, The silver paste includes 90 to 95 wt% of the silver nanoparticles and 5 to 10 wt% of the binder.

23. The ultrasonic sensor according to claim 21, wherein, The size of the silver nanoparticles ≤ 200 nm.

24. The ultrasonic sensor according to claim 18, wherein, The upper electrode and the lower electrode are formed using the silver paste and an ethanol-based solvent.

25. The ultrasonic sensor according to claim 18, wherein, The piezoelectric member includes polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

26. The ultrasonic sensor according to claim 18, wherein, The substrate is a plastic substrate.

27. The ultrasonic sensor according to claim 18, wherein, The support member includes brass or aluminum.

28. The ultrasonic sensor according to claim 18, further comprising: A conductive adhesive member disposed between the substrate and the piezoelectric member, wherein the conductive adhesive member includes at least one of a silicone-based adhesive, a conductive epoxy adhesive, an insulating epoxy adhesive, and an acrylic-based ultraviolet adhesive.

29. The ultrasonic sensor according to claim 28, wherein, The conductive adhesive member includes: A first conductive adhesive member disposed to contact the support member; and A second conductive adhesive member disposed to contact the lower electrode.

30. The ultrasonic sensor according to claim 29, wherein, The thickness of each of the first conductive adhesive member and the second conductive adhesive member ≤ 5 μm.

31. The ultrasonic sensor according to claim 18, further comprising: An ultrasonic sensor controller disposed adjacent to one side of the ultrasonic sensor and configured to control the ultrasonic sensor, wherein the ultrasonic sensor controller includes: A flexible printed circuit; An ultrasonic sensor integrated circuit mounted on one side of the flexible printed circuit; and The first wiring and the second wiring are installed on the other side of the flexible printed circuit and electrically connected to the surface of the ultrasonic sensor.

32. The ultrasonic sensor according to claim 31, wherein, The first wiring is disposed between the substrate and the lower electrode, and the second wiring contacts at least a part of the side surface of the upper electrode.

33. A display device, the display device comprising: A covering member, the covering member including a display area and an ultrasonic sensor area; A display device disposed on the rear surface of the covering member and overlapping with the display area; and The ultrasonic sensor according to any one of claims 1 to 32, the ultrasonic sensor being disposed on the rear surface of the covering member and overlapping with the ultrasonic sensor area.

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