Transparent electrostatic ultrasonic transducer and display device

Abstract

The application discloses a transparent electrostatic ultrasonic transducer and a display device, wherein the transducer increases the surface roughness of the vibrating diaphragm surface and / or the insulating layer surface, so that the phase relationship of the light waves reflected from the two interfaces changes rapidly in space when superimposed, or the light waves are diffusely reflected, so that a large-area and bright color coherent interference pattern cannot be formed. Through the scheme, the conditions for thin film interference can be effectively destroyed, the transparent electrostatic ultrasonic transducer no longer presents obvious rainbow stripes under white light, the visual appearance is improved, so that when the transparent electrostatic ultrasonic transducer is integrated with a display screen, visual interference on the display content is avoided, the user experience is improved, and the application is particularly suitable for applications with high requirements on visual quality, such as smart phones, tablet computers, vehicle-mounted displays and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of directional sound production, and in particular to a transparent electrostatic ultrasonic transducer and a display device. BACKGROUND

[0002] The main structure of the existing transparent electrostatic ultrasonic transducer generally includes a vibrating diaphragm, a fixed electrode, a micron-level air gap between the two, an insulating layer, and a support structure for forming the air gap. In order to obtain good acoustic performance, such as higher electromechanical conversion efficiency and sound pressure output, it is generally required that the air gap within the transducer unit has a high degree of uniformity.

[0003] However, when the thickness of the air gap is several orders of magnitude of the wavelength of visible light and very uniform, the inner surface of the vibrating diaphragm and the surface of the underlying insulating layer or fixed electrode form a structure similar to a Fabry-Perot interferometer. Under the irradiation of wide-spectrum white light (such as ambient light), light of different wavelengths interferes constructively or destructively at a certain angle and a certain air gap thickness, thereby presenting rainbow-colored interference fringes (i.e., an extension of the rainbow fringe or Newton's ring phenomenon) on the surface of the transducer, as shown in FIG. 1. Although this rainbow fringe is a representation of the uniformity of the air gap, when integrated with a display screen, it will seriously affect the visual effect of the display picture and the user experience, making the screen look greasy or have unnatural color spots, especially when the transducer area is large, the rainbow fringe phenomenon is more pronounced. Figure 1

[0004] The existing technology mainly focuses on optimizing the acoustic performance of the transducer and measuring its structural parameters, and there is no mature solution for how to eliminate or weaken this visual interference rainbow fringe problem caused by a highly uniform air gap. Therefore, it is urgent to develop a technical solution that can effectively eliminate or significantly reduce the rainbow fringes on the surface of a transparent electrostatic ultrasonic transducer while maintaining its original acoustic performance and transparency as much as possible to meet the visual requirements in display integration applications. SUMMARY

[0005] The present application relates to the technical field of directional sound production, and in particular to a transparent electrostatic ultrasonic transducer and a display device.

[0006] ​To achieve the above object, in one aspect, the present application provides a transparent electrostatic ultrasonic transducer, comprising a vibrating layer, a fixed electrode and a plurality of support structures, the vibrating layer comprising a vibrating membrane and a top electrode, the top electrode being arranged on the surface of the vibrating membrane close to the fixed electrode; the fixed electrode comprising a fixed bottom plate, a bottom electrode and an insulating layer, the bottom electrode being arranged on the surface of the fixed bottom plate close to the vibrating layer, the insulating layer being arranged on the surface of the bottom electrode close to the vibrating layer; the vibrating layer and the fixed electrode are in close contact with the frame, the support structures are located between the vibrating layer and the fixed electrode, and an air gap is formed between the vibrating layer and the fixed electrode under the support of the support structures; the haze and the first surface roughness of the lower surface of the vibrating membrane close to the top electrode and / or the upper surface of the vibrating membrane away from the top electrode are increased, the haze is 3%~50%, the first surface roughness is 0.1um~1.0um and is less than 10% of the thickness of the vibrating membrane, and / or the second surface roughness of the upper surface of the insulating layer close to the air gap is increased, the second surface roughness is 0.05um~2.0um and is less than 10% of the thickness of the insulating layer.

[0007] In a preferred embodiment, the increase of the haze and the first surface roughness of the lower surface of the vibrating membrane close to the top electrode and / or the upper surface of the vibrating membrane away from the top electrode comprises: forming a first micro-rough structure or adding a micro-rough layer on the lower surface and / or the upper surface of the vibrating membrane.

[0008] In a preferred embodiment, the micro-rough layer comprises a light scattering layer, the light scattering layer comprises an anti-glare AG layer, the anti-glare AG layer comprises a transparent adhesive layer containing micron-sized transparent particles; and / or the first micro-rough structure is formed by physical and / or chemical treatment of the surface of the vibrating membrane, the physical and / or chemical treatment includes one or a combination of more than two of plasma treatment, plasma etching, chemical etching, mechanical imprinting and mechanical knurling.

[0009] In a preferred embodiment, the vibrating membrane is a PET film with a thickness of 5um~500um, the thickness of the anti-glare AG layer is 1um~10um, the micron-sized transparent particles in the anti-glare AG layer include any one or a combination of more than two of silica particles, polymethyl methacrylate microspheres and polystyrene microspheres, the average particle size of the micron-sized transparent particles ranges from 1um to 10um, the transparent adhesive layer comprises an acrylic resin adhesive layer or a polyurethane resin adhesive layer, and / or the plasma treatment includes treating the vibrating membrane with plasma, the treatment power is 50W~300W and the treatment time is 10s~300s.

[0010] In a preferred embodiment, the way of increasing the second surface roughness of the upper surface of the insulating layer near the air gap comprises forming a second micro-rough structure on the upper surface of the insulating layer, or changing the preparation process of the insulating layer, which comprises forming the insulating layer by using a screen printing or inkjet printing process.

[0011] In a preferred embodiment, the second micro-rough structure is formed by physically and / or chemically processing the upper surface of the insulating layer, which comprises plasma processing or chemical etching.

[0012] In a preferred embodiment, in the plasma processing or chemical etching process, the material of the insulating layer is any one or any combination of two or more of silicon dioxide, silicon nitride, polyimide, parylene, SU-8 photoresist, and transparent OC photoresist, and the thickness is 0.5 μm to 10 μm; and / or, the plasma processing comprises processing the insulating layer by using plasma, the processing power is 50 W to 300 W, and the processing time is 30 s to 10 min.

[0013] In a preferred embodiment, in the preparation process, the material of the insulating layer is transparent insulating ink or transparent insulating ink added with nano- or micro-sized transparent fillers, and the nano- or micro-sized transparent fillers comprise silicon dioxide; and / or, the screen mesh number of the screen printing is 200 to 400, and the thickness of the insulating layer after printing is 1 μm to 15 μm.

[0014] In a preferred embodiment, if the material of the insulating layer is photoresist, the way of forming the second micro-rough structure on the upper surface of the insulating layer comprises exposing and developing the photoresist, or adding nano- or micro-sized transparent fillers in the photoresist, which comprise silicon dioxide; or performing thermal reflow topography modification or roughening treatment on the surface of the photoresist.

[0015] In another aspect, the present application provides a display device comprising a display screen and the above transparent electrostatic ultrasonic transducer, which is located on the outside of the display screen near the user side or on the inside of the display screen away from the user side or integrated in the display screen.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1、The present application increases the surface roughness of the diaphragm surface and / or the insulating layer surface, so that the phase relationship of the light waves reflected from the two interfaces changes rapidly in space when superimposed, or the light waves are diffusely reflected, so that a large-area, color-bright coherent interference pattern cannot be formed. By this scheme, the conditions for thin film interference can be effectively destroyed, so that the transparent electrostatic ultrasonic transducer no longer presents obvious rainbow stripes under white light, and the visual appearance is improved.

[0018] 2、The transparent electrostatic ultrasonic transducer after eliminating the rainbow stripes does not cause visual interference to the display content when integrated with the display screen, improves the user experience, and is especially suitable for applications with high requirements on visual quality, such as smart phones, tablet computers, vehicle-mounted displays, etc.

[0019] 3、The improvement method proposed in the present application is mostly based on existing mature thin film processing technologies (such as anti-glare AG coating, plasma treatment, screen printing, etc.), which is easy to integrate into the production process of the existing transparent electrostatic ultrasonic transducer, and the cost increase is controllable.

[0020] 4、Under the premise of reasonable control of processing parameters, the influence of the present application on the core acoustic performance (such as resonance frequency and sound pressure level) of the transducer and the overall transparency can be controlled within an acceptable range. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A schematic diagram of interference stripes presented by the existing transducer surface;

[0022] Figure 2 A specific structure schematic diagram of the transparent electrostatic ultrasonic transducer (a layer of micro-rough layer is additionally arranged on the upper and lower surfaces of the diaphragm) in another embodiment of the present application;

[0023] Figure 3 A specific structure schematic diagram of the transparent electrostatic ultrasonic transducer (a layer of micro-rough layer is additionally arranged on the lower surface of the diaphragm) in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of the laminated structure of the transparent electrostatic ultrasonic transducer combined with the display screen.

[0025] The reference signs are:

[0026] 10、transparent electrostatic ultrasonic transducer, 1、vibration layer, 11、diaphragm, 12、top electrode, 13、micro-rough layer, 2、fixed electrode, 21、fixed bottom plate, 22、bottom electrode, 23、insulating layer, 3、supporting structure, 4、air gap, 20、display screen. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application will be described in detail below, but it should be understood that the scope of the present application is not limited by the specific embodiments.

[0028] Unless otherwise clearly indicated, throughout the specification and claims, the terms "including", "includes" or "include" are not limited to the elements or components recited. They mean "comprising" or "comprises" and permit the inclusion of additional elements or components.

[0029] In combination Figure 2 and Figure 3 As shown in the figure, the transparent electrostatic ultrasonic transducer disclosed by the embodiment of the present application specifically comprises a vibrating layer 1, a fixed electrode 2 and a plurality of support structures 3, wherein the vibrating layer 1 and the fixed electrode 2 are attached to each other at the frame, the support structures 3 are located between the vibrating layer 1 and the fixed electrode 2, and an air gap 4 is formed between the vibrating layer 1 and the fixed electrode 2 under the support of the support structures 3. In operation, the vibrating layer 1 vibrates and emits sound under the action of the direct current bias voltage and alternating voltage loaded between the vibrating layer 1 and the fixed electrode 2.

[0030] Specifically, the vibrating layer 1 comprises a vibrating diaphragm 11 and a top electrode 12, the top electrode 12 is arranged on the surface of the vibrating diaphragm 11 close to the fixed electrode 2, and in implementation, the vibrating diaphragm 11 is usually a PET (i.e. polyethylene terephthalate) film, and of course, other transparent flexible materials such as PI (polyimide), PEN (polyethylene naphthalate) and the like can also be used. The fixed electrode 2 comprises a fixed bottom plate 21, a bottom electrode 22 and an insulating layer 23, the bottom electrode 22 is arranged on the surface of the fixed bottom plate 21 close to the vibrating layer 1, and the insulating layer 23 is arranged on the surface of the bottom electrode 22 close to the vibrating layer 1. In implementation, the fixed bottom plate 21 can be a glass substrate, and the bottom electrode 22 and the top electrode 12 can be transparent ITO (indium tin oxide) layers.

[0031] Preferably, based on the above transparent electrostatic ultrasonic transducer, microscale irregularities or scattering properties are introduced on the surface of the vibrating diaphragm 11 and / or the surface of the insulating layer 23 to increase the roughness of the two surfaces, so as to change the reflection and interference behavior of light at the air gap interface and destroy the conditions of large-area coherent interference. Specifically, a first micro-rough structure (not shown in the figure) is formed on the lower surface of the vibrating diaphragm 11 close to the top electrode 12 and / or the upper surface of the vibrating diaphragm 11 away from the top electrode 12, or a micro-rough layer 13 is additionally provided, which is hereinafter referred to as scheme one, and / or a second micro-rough structure (not shown in the figure) is formed on the upper surface of the insulating layer 23 close to the air gap 4, which is hereinafter referred to as scheme two.

[0032] Specifically, as in Scheme I, a first micro-rough structure or layer 13 is introduced on one or both surfaces (i.e. lower surface or upper surface or both) of the diaphragm 11 (typically a PET film), particularly the lower surface facing the air gap 4 or the upper surface facing the viewer, to increase its haze and first surface roughness, specifically to achieve a surface haze of 3% to 50% and a first surface roughness of 0.1 μm to 1.0 μm and less than 10% of the diaphragm thickness.

[0033] As in a specific embodiment, the diaphragm 11 is an optical grade PET film with a thickness of 5 μm to 500 μm, combined with Figure 2 and Figure 3 As shown in the PET film, the micro-rough layer 13 is added to the lower surface and / or upper surface of the PET film, the micro-rough layer 13 can be specifically a coated anti-glare (AG) layer, which can be coated on the surface of the PET film by roll coating, spraying, scraping, etc., and then cured (such as UV curing or thermal curing). Of course, it can also be selected from the market AG layer of PET film.

[0034] The thickness of the anti-glare AG layer can be specifically 1 μm to 10 μm, which usually includes a transparent adhesive layer containing micron-sized transparent particles. The micron-sized transparent particles can be specifically silica (SiO2) microspheres and / or polymer microspheres, and the polymer microspheres can be specifically polymethyl methacrylate (PMMA) microspheres, polystyrene (PS) microspheres, etc. The average particle size of the microsphere particles ranges from 1 μm to 10 μm. The transparent adhesive layer can be specifically an optically transparent resin layer, which can be specifically an acrylic resin, a polyurethane resin, etc. In this embodiment, the haze of the surface of the PET film can range from 3% to 50%, preferably from 5% to 30%. If the haze is too low, the improvement of the rainbow effect will not be obvious, and if it is too high, it may excessively affect the transparency and display clarity of the PET film. The surface roughness (Ra) of the PET film can be 0.1 μm to 1.0 μm, and it is less than 10% of the thickness of the PET film to avoid significant negative impact on the acoustic performance of the transducer.

[0035] For another example, in another specific embodiment, the diaphragm is also an optical grade PET film with a thickness of 5 μm to 500 μm. When the first micro-rough structure is formed on the lower surface and / or the upper surface of the PET film, the surface of the diaphragm can be treated by physical and / or chemical methods to form micro pits, bumps or textures, etc. to enhance light scattering. In practice, the physical and / or chemical methods include one or any two or more combinations of plasma treatment, plasma etching, chemical etching, mechanical imprinting, mechanical knurling. For example, in the plasma treatment and plasma etching method, the surface of the PET film can be treated by plasma of argon (Ar), oxygen (O2) or carbon tetrafluoride (CF4) or a mixture of two or more of these gases for a short time to form a nano-scale or micro-scale rough structure. The treatment power can be specifically 50 W to 300 W and the time can be specifically 10 s to 300 s. For example, in the chemical etching method, the surface of the PET film can be selectively etched by using appropriate chemical reagents (such as hydrofluoric acid). For example, in the mechanical imprinting and mechanical knurling method, the PET film can be imprinted by a mold with micro-texture.

[0036] Specifically, for example in solution two, the second surface roughness of the insulating layer 23 near the upper surface of the air gap 4 can be increased to 0.05 μm to 2.0 μm, which is less than 10% of the thickness of the insulating layer. In practice, the morphology of the upper surface of the insulating layer 23 can be changed to introduce a micro-scale height fluctuation, so that the thickness of the air gap 4 changes rapidly in a small area, thereby destroying the condition of forming uniform interference fringes. Specifically, a second micro-rough structure can be formed on the upper surface of the insulating layer 23, or the preparation process of the insulating layer 23 can be changed.

[0037] In this way, in practice, the material of the insulating layer 23 can be silicon dioxide (SiO2), silicon nitride (SiN xpolyimide (PI), parylene, SU-8 photoresist, transparent OC photoresist, transparent insulating ink, or any combination of two or more thereof, and has a thickness of 0.5 μm to 10 μm. In forming the second micro-rough structure on the upper surface of the insulating layer 23, the upper surface of the insulating layer 23 can be treated by physical and / or chemical methods. In practice, the physical and / or chemical methods include plasma treatment or chemical etching, i.e., the upper surface of the insulating layer 23 is treated by plasma or etched by chemicals to form the second micro-rough structure on the surface. For example, in the plasma treatment, the surface of the insulating layer 23 can be treated by argon (Ar), oxygen (O2) or carbon tetrafluoride (CF4) plasma or a mixture of two or more thereof for a short time to form a nano- or micro-rough structure. The treatment power can be 50 W to 500 W, and the treatment time can be 30 s to 10 min. In this embodiment, the surface roughness (Ra) of the insulating layer 23 can be 50 nm to 800 nm, preferably 100 nm to 500 nm, which is sufficient to cause a significant local change in the optical path difference in the visible wavelength scale (about 400 nm to 700 nm), but the surface roughness of the insulating layer 23 is less than 10% of the thickness to avoid a significant negative impact on the acoustic performance of the transducer.

[0038] For example, in the chemical etching, a suitable etching solution and etching time can be selected according to the material of the insulating layer 23 to selectively etch the surface of the insulating layer 23 to achieve the target roughness. The etching solution can be a conventional hydrofluoric acid etching solution, and the etching time is determined according to the target roughness, which is not limited in the present application.

[0039] If the photoresist is used as the material of the insulating layer 23 or the support structure 3, the surface roughness of the photoresist can be increased by adjusting the exposure and development conditions or adding nano- or micro-sized transparent fillers, such as silicon dioxide, to the photoresist, or by post-treatment of the surface of the photoresist, such as thermal reflow topography modification or roughening treatment.

[0040] For example, the surface roughness of the insulating layer 23 can be changed by changing the preparation process of the insulating layer 23. In the implementation, unlike the existing insulating layer 23 which is prepared by a process such as spin coating or evaporation that tends to form a smooth surface, the insulating layer 23 is prepared by a process such as screen printing or inkjet printing to deposit a transparent insulating ink material, which tends to form a surface with certain micro relief. In the implementation, the transparent insulating ink can be used, or a transparent insulating ink with a small amount of nano or micro transparent fillers can be used to assist in adjusting the roughness of the insulating layer 23. The transparent insulating ink can be a UV-cured or thermally cured ink based on acrylate, epoxy resin, or polyurethane. In the screen printing process, the screen mesh can be 200-400 mesh, the thickness of the insulating layer 23 after printing can be 1-15 μm, and the surface roughness of the insulating layer 23 can be 0.1-2 μm.

[0041] Of course, according to actual needs, a plurality of methods in the first and second solutions can be combined to achieve the best rainbow stripe elimination effect and visual experience. For example, the PET film coated with the anti-glare AG layer and the roughened insulating layer 23 can be used at the same time.

[0042] The following three specific embodiments are used to specifically introduce the above-mentioned solution of the transparent electrostatic ultrasonic transducer for eliminating rainbow stripes.

[0043] Embodiment 1

[0044] A transparent electrostatic ultrasonic transducer disclosed in the embodiment 1 of the present application is prepared as follows. The fixed bottom plate 21 of the fixed electrode 2 is made of a Corning Gorilla glass substrate with a thickness of 0.7 mm, and a layer of ITO with a thickness of 100 nm is deposited on the glass substrate by magnetron sputtering as the bottom electrode 22. A layer of transparent photosensitive polyimide (PSPI) with a thickness of 2 μm is spin-coated on the bottom electrode 22 as the insulating layer 23, and an array of support columns with a height of 8 μm, a diameter of 50 μm, and a spacing of 1 mm is made on the insulating layer 23 as the support structure 3 by coating and photolithography process (e.g., using SU-8 photoresist), and the insulating layer 23 and the support structure 3 are cured, at which time the surface of the insulating layer 23 is smooth.

[0045] The vibration layer 1 is prepared as follows. In the embodiment 1, a PET film with an AG coating on one side is selected, the thickness of the PET film is 12 μm, the AG coating is composed of SiO2 particles with an average particle size of 3 μm and an acrylic resin adhesive layer, and the thickness of the coating is about 4 μm. The haze of the PET film with the AG coating is 15%, and the total light transmittance is >88. A layer of ITO with a thickness of 80 nm is sputtered on the non-AG side (i.e., the smooth side) of the PET film as the top electrode 12.

[0046] Lamination: The vibrating layer 1 (with its AG side facing out, i.e. towards the observer, or with its AG side facing the air gap) is covered on the fixed electrode 2 with the support structure 3, fixed by edge bonding, and an appropriate tension is applied to form the air gap 4.

[0047] The transparent electrostatic ultrasonic transducer formed in this embodiment 1 is observed under a fluorescent lamp or an LED lamp, and no obvious rainbow stripes are observed on the surface, and the visual effect is clear. As a comparison, if a common high-transparency PET film (with a haze < 1) is used, obvious rainbow stripes can be observed.

[0048] Embodiment 2

[0049] The transparent electrostatic ultrasonic transducer disclosed in this embodiment 2 is prepared in the same way as the fixed base plate 21 and the bottom electrode 22 in embodiment 1, which will not be repeated here. Different from embodiment 1, the preparation process of the insulating layer 23 in this embodiment is as follows: a layer of SiO2 with a thickness of 3 μm is deposited on the bottom electrode 22 as the insulating layer 23 by PECVD, and the fixed base plate 21 with the insulating layer 23 is placed in a reactive ion etching (RIE) device, and a mixed gas of CF4 and O2 (for example, with a ratio of 4:1, and a total flow rate of 50 sccm) is introduced, and a micro-rough structure is formed on the surface of the SiO2 under the conditions of a radio frequency power of 150 W and a pressure of 10 Pa, and the average surface roughness (Ra) of the micro-rough structure is about 200 nm.

[0050] Then, the support column array with a height of 8 μm, a diameter of 50 μm and a spacing of 1 mm is prepared on the roughened insulating layer 23 as the support structure 3 by a photolithography process (for example, using SU-8 photoresist).

[0051] Preparation of the vibrating layer 1: In this embodiment 2, a common high-transparency PET film is selected, the thickness of the PET film is 12 μm, the haze of the PET film is less than 1%, and the total light transmittance is greater than 88%. A layer of ITO with a thickness of 80 nm is sputtered on one side of the PET film as the top electrode 12.

[0052] Lamination: In the same way as in embodiment 1, the vibrating layer 1 (with the top electrode 12 facing the air gap) is covered on the fixed electrode 2 with the support structure 3 and the roughened insulating layer 23, fixed by edge bonding, and an appropriate tension is applied to form the air gap 4.

[0053] The transparent electrostatic ultrasonic transducer formed in this embodiment 2 has a significantly reduced rainbow stripe phenomenon on the surface compared with the device without roughening treatment of the insulating layer. If the plasma treatment parameters are further optimized, or combined with a slight fogging treatment of the vibrating membrane, the rainbow stripes can be basically eliminated.

[0054] Embodiment 3

[0055] A transparent electrostatic ultrasonic transducer is disclosed in embodiment 3 of the present application. The preparation of the fixed bottom plate 21 and the bottom electrode 22 is the same as in embodiment 1, which will not be repeated here. Unlike embodiments 1 and 2, the preparation process of the insulating layer 23 and the support structure 3 in this embodiment is as follows: using a 300-mesh screen, the pattern containing the insulating layer 23 and the support structure 3 is directly printed on the bottom electrode 22 by screen printing. The design thickness of the insulating layer 23 is 3 μm, and the design height of the support structure 3 is 10 μm (achieved by multiple overprinting or using a thick screen). Then, UV curing is performed. The surface of the insulating layer 23 formed by screen printing itself has a certain microscopic unevenness, for example, the roughness Ra is in the range of 0.2 μm to 1 μm.

[0056] Preparation and bonding of the vibration layer 1: the same as in embodiment 2, which will not be repeated here.

[0057] The transparent electrostatic ultrasonic transducer prepared in embodiment 3 effectively suppresses the generation of rainbow stripes due to the microscopic unevenness of the surface of the insulating layer 23 and the sidewall of the support structure 3. This method simplifies the preparation steps of the support structure 3 and the insulating layer 23.

[0058] In combination Figure 4 As shown in the figure, the present application also discloses a display device, which comprises a display screen 20 and the above-mentioned transparent electrostatic ultrasonic transducer 10, wherein the transparent electrostatic ultrasonic transducer 10 is located on the outside of the display screen 20 close to the user side or on the inside of the display screen 20 away from the user side or integrated in the display screen 20.

[0059] The advantages of the present application are as follows: 1. By increasing the surface roughness of the vibration membrane surface and / or the insulating layer surface, the phase relationship of the light waves reflected from the two interfaces changes rapidly in space when superimposed, or the light waves are diffusely reflected, so that a large-area and color-bright coherent interference pattern cannot be formed. Through this scheme, the conditions for thin-film interference can be effectively destroyed, so that the transparent electrostatic ultrasonic transducer no longer presents obvious rainbow stripes under white light, improving its visual appearance. 2. After the elimination of rainbow stripes, the transparent electrostatic ultrasonic transducer integrated with the display screen will not cause visual interference to the display content, improving the user experience, and is particularly suitable for applications with high requirements for visual quality, such as smart phones, tablet computers, and vehicle-mounted displays. 3. Most of the improvement methods proposed in the present application are based on existing mature thin-film processing technologies (such as anti-glare AG coating, plasma treatment, screen printing, etc.), which are easy to integrate into the production process of existing transparent electrostatic ultrasonic transducers, and the cost increase is controllable. 4. Under the premise of reasonable control of processing parameters, the influence on the core acoustic performance (such as resonance frequency and sound pressure level) of the transducer and the overall transparency can be controlled within an acceptable range.

[0060] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A transparent electrostatic ultrasonic transducer, characterized in that, the transparent electrostatic ultrasonic transducer comprises a vibrating layer, a fixed electrode and a plurality of support structures, the vibrating layer comprises a vibrating membrane and a top electrode, the top electrode is arranged on the surface of the vibrating membrane close to the fixed electrode; the fixed electrode comprises a fixed base plate, a bottom electrode and an insulating layer, the bottom electrode is arranged on the surface of the fixed base plate close to the vibrating layer, and the insulating layer is arranged on the surface of the bottom electrode close to the vibrating layer; the vibrating layer and the fixed electrode are in contact with each other at the frame, the support structures are located between the vibrating layer and the fixed electrode, and an air gap is formed between the vibrating layer and the fixed electrode under the support of the support structures; a haze and a first surface roughness of the lower surface of the vibrating membrane close to the top electrode and / or the upper surface of the vibrating membrane away from the top electrode are increased, the haze is 3% to 50%, the first surface roughness is 0.1 μm to 1.0 μm and less than 10% of the thickness of the vibrating membrane, and / or a second surface roughness of the upper surface of the insulating layer close to the air gap is increased, the second surface roughness is 0.05 μm to 2.0 μm and less than 10% of the thickness of the insulating layer.

2. A transparent electrostatic ultrasonic transducer as claimed in claim 1, characterized in that, The increase of the haze and the first surface roughness of the lower surface of the vibrating membrane close to the top electrode and / or the upper surface of the vibrating membrane away from the top electrode comprises forming a first micro-rough structure on the lower surface and / or the upper surface of the vibrating membrane or adding a micro-rough layer. 3.The transparent electrostatic ultrasonic transducer of claim 2, characterized in that, the micro-rough layer comprises a light scattering layer, the light scattering layer comprises an anti-glare AG layer, and the anti-glare AG layer comprises a transparent adhesive layer containing micron-sized transparent particles; and / or the first micro-rough structure is formed by physical and / or chemical treatment of the surface of the vibrating membrane, and the physical and / or chemical treatment comprises one or a combination of two or more of plasma treatment, plasma etching, chemical etching, mechanical imprinting and mechanical knurling. 4.The transparent electrostatic ultrasonic transducer of claim 3, characterized in that, the vibrating membrane is a PET membrane with a thickness of 5 μm to 500 μm, the anti-glare AG layer has a thickness of 1 μm to 10 μm, the micron-sized transparent particles in the anti-glare AG layer comprise any one or a combination of two or more of silica particles, polymethyl methacrylate microspheres and polystyrene microspheres, the average particle size of the micron-sized transparent particles ranges from 1 μm to 10 μm, and the transparent adhesive layer comprises an acrylic resin adhesive layer or a polyurethane resin adhesive layer; and / or the plasma treatment comprises treating the vibrating membrane with plasma, the treatment power is 50 W to 300 W, and the treatment time is 10 s to 300 s.

5. A transparent electrostatic ultrasonic transducer as claimed in claim 1, characterized in that, The way of increasing the second surface roughness of the upper surface of the insulating layer close to the air gap comprises forming a second micro-rough structure on the upper surface of the insulating layer or changing the preparation process of the insulating layer, and the preparation process comprises forming the insulating layer by screen printing or inkjet printing.

6. A transparent electrostatic ultrasonic transducer as claimed in claim 5, characterized in that The second micro-rough structure is formed by physically and / or chemically processing the upper surface of the insulating layer, and the physical and / or chemical processing includes plasma processing or chemical etching. 7.The transparent electrostatic ultrasonic transducer of claim 6, wherein, In the plasma processing or chemical etching process, the material of the insulating layer is any one or any combination of two or more of silicon dioxide, silicon nitride, polyimide, parylene, SU-8 photoresist, and transparent OC photoresist, and the thickness is 0.5 μm to 10 μm; and / or, The plasma processing includes processing the insulating layer by plasma, and the processing power is 50 W to 300 W, and the processing time is 30 s to 10 min. 8.The transparent electrostatic ultrasonic transducer of claim 5, wherein, In the preparation process, the material of the insulating layer is transparent insulating ink or transparent insulating ink added with nano- or micro-sized transparent fillers, and the nano- or micro-sized transparent fillers include silicon dioxide; and / or, The silk screen printing has a silk screen mesh number of 200 to 400, and the thickness of the insulating layer after printing is 1 μm to 15 μm.

9. A transparent electrostatic ultrasonic transducer as claimed in claim 5, characterized in that, If the material of the insulating layer is photoresist, the method of forming the second micro-rough structure on the upper surface of the insulating layer includes exposing and developing the photoresist or adding nano- or micro-sized transparent fillers to the photoresist, and the nano- or micro-sized transparent fillers include silicon dioxide; or performing thermal reflow topography modification or roughening treatment on the surface of the photoresist.

10. A display device, characterized by comprising: The display screen and the transparent electrostatic ultrasonic transducer of any one of claims 1 to 9 are located on the outer side of the display screen close to the user side or on the inner side of the display screen away from the user side or integrated in the display screen.

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