Electrostatic film ultrasonic transducer

Abstract

The electrostatic film ultrasonic transducer comprises a vibration layer, a non-vibration layer, a supporting column and an insulating layer, the frame of the vibration layer is attached to the frame of the non-vibration layer, and an air gap is formed between the vibration layer and the non-vibration layer through the supporting column after the frame of the vibration layer is attached to the frame of the non-vibration layer. The insulating layer is located between the supporting column and the first conductive layer or between the supporting column and the bottom electrode, the air gap is vacuum or filled with gas not prone to ionization, and / or the insulating layer is not prone to ionization. According to the electrostatic film ultrasonic transducer, air ionization is not easy to occur in the air gap, and / or charges are not easy to lose on the insulating layer, so that the accumulation of static electricity on the surface of the insulating layer can be reduced, the influence of the charges generated by air ionization on air partial pressure is greatly reduced, and the reliability and sound pressure of the electrostatic film ultrasonic transducer can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of directional sound generation, in particular to an electrostatic thin film ultrasonic transducer. Background Art

[0002] Electrostatic thin film ultrasonic transducer is also called capacitive thin film ultrasonic transducer. It uses the electrostatic force generated by the upper and lower electrodes to drive the film to vibrate, thereby radiating ultrasonic waves.

[0003] The structure of a common electrostatic thin film ultrasonic transducer 100 is generally as follows: Figure 1 As shown, it includes structures such as a film 101, a top electrode 102, a support column 103, an insulating layer 104, a bottom electrode 105 and a fixed bottom plate 106 from top to bottom, and an air gap 107 is formed between the top electrode 102 and the insulating layer 104. A DC bias voltage Vdc and an AC voltage Vac are passed between the top electrode 102 and the bottom electrode 105 to drive the film 101 to vibrate and generate sound.

[0004] However, when the input voltage increases, the air in the air gap will be ionized. The ionization will increase the conductivity of the air and generate an additional electric field. The additional electric field will cause the partial pressure in the air to decrease, and the ultrasonic sound pressure radiated by the electrostatic thin film ultrasonic transducer will decrease, thereby reducing the performance of the transducer (including reliability and sound pressure performance).

[0005] Therefore, how to reduce the impact of air ionization on the reliability and sound pressure of electrostatic thin film ultrasonic transducers is a problem that needs to be solved. Utility Model Content

[0006] The utility model aims to provide an electrostatic thin film ultrasonic transducer which can effectively reduce the influence of air ionization on the reliability and sound pressure of the electrostatic thin film ultrasonic transducer.

[0007] To achieve the above object, the utility model proposes an electrostatic thin film ultrasonic transducer, comprising:

[0008] A vibration layer, the vibration layer comprising a thin film and a top electrode, wherein the top electrode is entirely disposed on a surface of the thin film close to the non-vibration layer;

[0009] A non-vibration layer is attached to the frame of the vibration layer, and the non-vibration layer includes a fixed bottom plate and a bottom electrode, wherein the bottom electrode is formed entirely on a surface of the fixed bottom plate close to the vibration layer;

[0010] A support column, wherein the support column is located between the top electrode and the bottom electrode, and after the vibration layer and the non-vibration layer frame are attached to each other, an air gap required for the vibration layer to vibrate up and down and generate sound is formed between the support column and the non-vibration layer;

[0011] an insulating layer, the insulating layer being located between the support pillar and the top electrode or between the support pillar and the bottom electrode;

[0012] The air gap is vacuum or filled with a gas that is not easily ionized, and / or the insulating layer is an insulating layer that is not easily ionized.

[0013] In a preferred embodiment, the gas that is not easily ionized is at least any one of the inert gases or nitrogen, and the inert gases include helium, neon, argon, krypton, xenon and radon.

[0014] In a preferred embodiment, the insulating layer includes a first insulating layer, the first insulating layer is located between the support column and the top electrode or between the support column and the bottom electrode, and the first insulating layer is an antistatic layer.

[0015] In a preferred embodiment, the insulating layer includes a first insulating layer and a second insulating layer, the second insulating layer is located between the support column and the top electrode or between the support column and the bottom electrode, the first insulating layer is located between the second insulating layer and the top electrode or between the second insulating layer and the bottom electrode, the first insulating layer is an ink layer, and the second insulating layer is an antistatic layer.

[0016] In a preferred embodiment, the insulating layer includes a first insulating layer and a second insulating layer, and the electrostatic thin film ultrasonic transducer also includes an intermediate electrode, the intermediate electrode is arranged on the surface of the bottom electrode close to the vibration layer and is insulated and isolated from the bottom electrode by the first insulating layer, and the intermediate electrode and the top electrode are insulated and isolated by the second insulating layer, the first insulating layer is an ink layer, and the second insulating layer is an antistatic layer.

[0017] In a preferred embodiment, the antistatic layer is an ink layer doped with antistatic particles or conductive particles.

[0018] In a preferred embodiment, the antistatic microspheres include any one of silicon dioxide spherical powder, polytetrafluoroethylene spherical powder, acrylic copolymer spherical powder and organic compound spherical powder; and the conductive particles include at least silicon spherical powder.

[0019] In a preferred embodiment, the antistatic layer is a polytetrafluoroethylene layer.

[0020] In a preferred embodiment, the middle electrode is grounded through a load, and a DC bias voltage and an AC voltage are connected between the top electrode and the bottom electrode.

[0021] In a preferred embodiment, a DC bias voltage and an AC voltage are connected between the top electrode and the bottom electrode.

[0022] Compared with the prior art, the utility model has the following beneficial effects:

[0023] The utility model designs the air gap to be a vacuum or to be filled with a gas that is not easily ionized, and / or sets the insulating layer to be an insulating layer that is not easily ionized, so that air ionization is not likely to occur in the air gap, an additional electric field is not likely to be generated, and / or the insulating layer is not likely to lose charge, thereby reducing the accumulation of static electricity on the surface of the insulating layer, thereby greatly reducing the influence of the charge generated by air ionization on the air partial pressure, and further improving the reliability and sound pressure of the electrostatic thin film ultrasonic transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of an existing electrostatic thin film ultrasonic transducer;

[0025] Figure 2 It is a schematic structural diagram of an electrostatic thin film ultrasonic transducer (doped insulating layer) in a specific embodiment of the utility model;

[0026] Figure 3 It is a structural schematic diagram of an electrostatic thin film ultrasonic transducer (with an insulating layer) in a specific embodiment of the utility model;

[0027] Figure 4 It is a schematic diagram of the structure of an electrostatic thin film ultrasonic transducer (with an intermediate electrode) in a specific embodiment of the utility model;

[0028] Figure 5 It is a simulation schematic diagram of the air layer voltage in a specific embodiment of the utility model.

[0029] The accompanying drawings are marked as follows:

[0030] 1. Vibration layer, 11. Thin film, 12. Top electrode, 2. Non-vibration layer, 21. Fixed base plate, 22. Bottom electrode, 3. Support column, 4. Insulation layer, 41. First insulation layer, 42. Second insulation layer, 5. Air gap, 6. Antistatic particles / conductive particles, 7. Middle electrode. DETAILED DESCRIPTION

[0031] The specific implementation modes of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0032] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0033] Combination Figure 2 to Figure 4As shown, an electrostatic thin film ultrasonic transducer disclosed by the utility model comprises a vibration layer 1, a non-vibration layer 2, a support column 3 and an insulating layer 4, wherein the frames of the vibration layer 1 and the non-vibration layer 2 are fitted together, and an air gap 5 is formed between the vibration layer 1 and the non-vibration layer 2 through the support column 3. The utility model designs the air gap 5 to be a vacuum or filled with a gas that is not easily ionized, and / or sets the insulating layer 4 as an insulating layer 4 that is not easily ionized, so that air ionization is not easy to occur in the air gap 5, an additional electric field is not generated, and / or the insulating layer 4 is not easy to lose charge, thereby reducing the accumulation of static electricity on the surface of the insulating layer 4, thereby greatly reducing the influence of the charge generated by air ionization on the air partial pressure, and further improving the reliability and sound pressure of the electrostatic thin film ultrasonic transducer.

[0034] The vibration layer 1 serves as an acoustic vibration layer, which specifically includes a film 11 and a top electrode 12. In this embodiment, the film 11 here can be implemented by a flexible film, such as a PET film. The top electrode 12 is formed on the surface of the film 11 close to the non-vibration layer 2. During implementation, the top electrode 12 can be implemented by a high-transmittance material such as nanosilver, indium tin oxide, metalmesh, carbon nanotubes or graphene, or a non-transparent conductive material such as copper or copper-doped oxide or silver or gold.

[0035] The non-vibration layer 2 serves as a non-vibration substrate layer, which specifically includes a fixed bottom plate 21 and a bottom electrode 22, wherein the bottom electrode 22 is entirely formed on the surface of the fixed bottom plate 21 close to the vibration layer 1. During implementation, the fixed bottom plate 21 can be made of glass, the same as the top electrode 12, and the bottom electrode 22 can also be made of high-transmittance materials such as nanosilver, indium tin oxide, metalmesh, carbon nanotubes or graphene, or can be a non-transparent conductive material: such as copper or copper-doped oxide or silver or gold, etc.

[0036] In this embodiment, the support column 3 is located between the top electrode and the bottom electrode 22. After the vibration layer 1 and the non-vibration layer 2 are attached to each other, an air gap 5 is formed between the support column 3 and the non-vibration layer 2 for the vibration layer 1 to vibrate up and down and generate sound. During implementation, the support column 3 can be formed on the surface of the top electrode close to the non-vibration layer 2, or on the surface of the bottom electrode 22 close to the vibration layer 1. The support column 3 is specifically a plurality of insulating bumps (not shown) arranged at intervals.

[0037] The insulating layer 4 is formed entirely between the support column 3 and the top electrode or between the support column 3 and the bottom electrode 22 , and is used to insulate and isolate the top electrode from the bottom electrode 22 after the vibration layer 1 and the non-vibration layer 2 are frame-bonded.

[0038] In order to reduce the air ionization in the air gap when the voltage is applied to the electrostatic thin film ultrasonic transducer, the air gap 5 and the insulating layer 4 can be improved and designed. When the air gap 5 is improved, in one embodiment, the air gap 5 can be set to a vacuum state. Specifically, a vacuum state can be formed in the air gap 5 by evacuating the air. Air ionization will not occur in the vacuum state, thereby avoiding the influence of air ionization on the sound pressure and reliability performance of the electrostatic thin film ultrasonic transducer. The air gap 5 can also be filled with a gas that is not easy to ionize. These gases can be any one of the inert gases or nitrogen, wherein the inert gases generally include helium, neon, argon, krypton, xenon and radon.

[0039] When improving the design of the insulating layer 4, the insulating layer 4 itself may be improved, or the performance of the insulating layer 4 may be improved by adding other structures. Figure 2 As shown, in one embodiment, antistatic particles can be doped into the insulating layer 4. Specifically, if the insulating layer 4 is an ink layer, antistatic particles can be doped into the ink layer to make it difficult for the ink layer surface to accumulate static electricity. During implementation, the antistatic particles 6 can include any one of silicon dioxide spherical powder, polytetrafluoroethylene spherical powder, acrylic copolymer spherical powder and organic compound spherical powder. In other alternative embodiments, conductive particles 6 can also be doped into the insulating layer 4, such as doping conductive particles 6 into the ink layer, and the conductive particles 6 can specifically be silicon spherical powder. The static electricity on the surface of the insulating layer 4 is led out by the conductive particles 6. Or in another alternative embodiment, the insulating layer 4 can also be directly implemented with an antistatic coating, such as a polytetrafluoroethylene layer. These materials are stable in nature, and the materials are not easy to lose charge, which can effectively reduce the accumulation of static electricity. For an electrostatic transducer, since positive charges will not accumulate on the surface, an electric field will not be generated, resulting in a decrease in the partial pressure in the air. Therefore, even under high pressure, the performance of the electrostatic thin film ultrasonic transducer will not be reduced.

[0040] When the performance of the insulating layer 4 is improved by adding other structures, such as Figure 3As shown, in one specific embodiment, an additional insulating layer is added on the existing insulating layer, that is, the insulating layer includes a first insulating layer 41 and a second insulating layer 42, wherein the second insulating layer 42 is located between the support column 3 and the top electrode 12 or between the support column 3 and the bottom electrode 22, and the first insulating layer 41 is located between the second insulating layer 42 and the top electrode 12 or between the second insulating layer 42 and the bottom electrode 22. During implementation, the first insulating layer 41 can be an ink layer, and the second insulating layer 42 can be an antistatic layer. Like the above-mentioned insulating layer, the antistatic layer here can adopt the above-mentioned ink layer doped with antistatic particles or doped with conductive particles, or can be directly implemented by an antistatic coating. Please refer to the above description and no further details will be given here.

[0041] In the above embodiment, a DC bias voltage Vdc and an AC voltage Vac are connected between the top electrode 12 and the bottom electrode 22 .

[0042] Or in other alternative embodiments, reducing air ionization can be achieved by adding a conductive layer. Figure 4 As shown, an intermediate electrode 7 is added on the bottom electrode 22, wherein the bottom electrode 22 and the intermediate electrode 7 are insulated and isolated by a first insulating layer 41, and the top electrode 12 and the intermediate electrode 7 are insulated and isolated by a second insulating layer 42. In this embodiment, these two insulating layers can be directly implemented by using an existing ink layer, or by using the ink layer doped with antistatic particles or doped with conductive particles as described above, or by directly using an antistatic coating, which is not limited by the present invention. In this embodiment, the key point is to ground the intermediate electrode through a load R, so as to quickly dissipate the static charge on the insulating layer. At the same time, a DC bias voltage Vdc and an AC voltage Vac are connected between the top electrode 12 and the bottom electrode 22.

[0043] After simulation, Figure 5 Through the above embodiment, when 300V is applied to both ends of the transducer electrode, the partial pressure in the air increases over time and eventually tends to be stable, that is, the sound of the transducer will not become smaller, and the reliability and sound pressure performance are stable.

[0044] The advantage of the utility model is that the utility model makes it difficult for air ionization to occur in the air gap and / or the insulating layer to lose charge by designing the air gap to be vacuum or filled with a gas that is not easily ionized and / or setting the insulating layer to be an insulating layer that is not easily ionized, thereby reducing the accumulation of static electricity on the surface of the insulating layer, thereby greatly reducing the influence of the charge generated by air ionization on the air partial pressure, and further improving the reliability and sound pressure of the electrostatic thin film ultrasonic transducer.

[0045] The foregoing description of specific exemplary embodiments of the utility model is for the purpose of illustration and illustration. These descriptions are not intended to limit the utility model to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the utility model and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the utility model and various different options and changes. The scope of the utility model is intended to be defined by the claims and their equivalents.

[0046] The foregoing description of specific exemplary embodiments of the utility model is for the purpose of illustration and illustration. These descriptions are not intended to limit the utility model to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the utility model and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the utility model and various different options and changes. The scope of the utility model is intended to be defined by the claims and their equivalents.

Claims

1. An electrostatic thin film ultrasonic transducer, characterized in that: include: A vibration layer, the vibration layer comprising a thin film and a top electrode, wherein the top electrode is entirely disposed on a surface of the thin film close to the non-vibration layer; A non-vibration layer is attached to the frame of the vibration layer, and the non-vibration layer includes a fixed bottom plate and a bottom electrode, wherein the bottom electrode is formed entirely on a surface of the fixed bottom plate close to the vibration layer; A support column, wherein the support column is located between the top electrode and the bottom electrode, and after the vibration layer and the non-vibration layer frame are attached to each other, an air gap required for the vibration layer to vibrate up and down and generate sound is formed between the support column and the non-vibration layer; an insulating layer, the insulating layer being located between the support pillar and the top electrode or between the support pillar and the bottom electrode; The air gap is vacuum or filled with a gas that is not easily ionized, and / or the insulating layer is an insulating layer that is not easily ionized.

2. An electrostatic thin film ultrasonic transducer as claimed in claim 1, characterized in that: The gas that is not easily ionized is at least any one of the inert gases or nitrogen, and the inert gases include helium, neon, argon, krypton, xenon and radon.

3. An electrostatic thin film ultrasonic transducer as claimed in claim 1, characterized in that: The insulating layer includes a first insulating layer, the first insulating layer is located between the supporting column and the top electrode or between the supporting column and the bottom electrode, and the first insulating layer is an antistatic layer.

4. An electrostatic thin film ultrasonic transducer as claimed in claim 1, characterized in that: The insulating layer includes a first insulating layer and a second insulating layer, the second insulating layer is located between the support column and the top electrode or between the support column and the bottom electrode, the first insulating layer is located between the second insulating layer and the top electrode or between the second insulating layer and the bottom electrode, the first insulating layer is an ink layer, and the second insulating layer is an antistatic layer.

5. The electrostatic thin film ultrasonic transducer according to claim 1, characterized in that: The insulating layer includes a first insulating layer and a second insulating layer. The electrostatic thin film ultrasonic transducer also includes an intermediate electrode. The intermediate electrode is arranged on the surface of the bottom electrode close to the vibration layer and is insulated and isolated from the bottom electrode by the first insulating layer. The intermediate electrode and the top electrode are insulated and isolated by the second insulating layer. The first insulating layer is an ink layer, and the second insulating layer is an antistatic layer.

6. An electrostatic thin film ultrasonic transducer according to any one of claims 3 to 5, characterized in that: The antistatic layer is a polytetrafluoroethylene layer.

7. An electrostatic thin film ultrasonic transducer as claimed in claim 5, characterized in that: The middle electrode is grounded through a load, and a DC bias voltage and an AC voltage are connected between the top electrode and the bottom electrode.

8. An electrostatic thin film ultrasonic transducer as claimed in claim 3 or 4, characterized in that: A direct current bias voltage and an alternating current voltage are connected between the top electrode and the bottom electrode.

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