Vibrating diaphragm, electrostatic ultrasonic transducer and electronic equipment

Abstract

The utility model discloses a vibrating diaphragm, electrostatic ultrasonic transducer and electronic equipment, the vibrating diaphragm comprises a central diaphragm part and a thinning part, the thinning part is located at the edge of the central diaphragm part, the thickness of the thinning part is smaller than that of the central diaphragm part, part of the position of the thinning part is fixed, and the rest part and the central diaphragm part integrally vibrate and produce sound. According to the utility model, by optimizing the structural design of the electrostatic film ultrasonic transducer, the effective vibration area proportion of the vibrating diaphragm is improved, and the sound pressure level of the electrostatic film ultrasonic transducer is further improved.

Description

Technical Field

[0001] This utility model relates to the field of ultrasonic transducer technology, specifically to a diaphragm, an electrostatic ultrasonic transducer, and an electronic device. Background Technology

[0002] Electrostatic thin-film ultrasonic transducers, also known as capacitive thin-film ultrasonic transducers, utilize the electrostatic force generated by the upper and lower electrodes to drive the thin film to vibrate, thereby radiating ultrasonic waves.

[0003] Figure 1 The diagram illustrates the structure of an electrostatic thin-film ultrasonic transducer provided in the related art. From top to bottom, the structure includes: a thin film, a top electrode, a support column, an air gap, an insulating layer, a bottom electrode, and a fixed base plate. A DC bias voltage Vdc and an AC voltage Vac are applied between the top and bottom electrodes. The electrostatic force generated between the top and bottom electrodes can be used to drive the thin film vibration.

[0004] However, the diaphragm in the above design does not undergo piston-like motion, and its effective vibration area ratio is relatively low, generally around 50% to 70%. Therefore, how to increase the effective vibration area of ​​the diaphragm, and thus improve the overall sound pressure level of the electrostatic thin-film ultrasonic transducer, is a problem that needs to be studied. Utility Model Content

[0005] The purpose of this invention is to provide a diaphragm, an electrostatic ultrasonic transducer, and an electronic device to solve the problem of low effective vibration area of ​​existing diaphragms.

[0006] To achieve the above objectives, on the one hand, this utility model proposes a diaphragm for an electrostatic ultrasonic transducer, including a central diaphragm and a thinning portion. The thinning portion is located at the edge of the central diaphragm and its thickness is less than that of the central diaphragm. Part of the thinning portion is fixed, and the remaining portion vibrates and generates sound as a whole with the central diaphragm.

[0007] In a preferred embodiment, the central membrane portion and the thinning portion are integrally formed from a single thin film.

[0008] In a preferred embodiment, the film is a PET film, a PI film, a PVDF film, or a PTFE film, and / or, the thickness of the thinned portion is 1% to 20% of the thickness of the central film portion, and / or, the area of ​​the thinned portion is 1% to 10% of the area of ​​the entire diaphragm, and / or, the thickness of the central film portion is 1µm to 1mm.

[0009] In a preferred embodiment, the diaphragm includes a separate thin film body and a thickened layer. The thickened layer is located in the middle of the upper surface and / or lower surface of the thin film body. The portion of the thin film body corresponding to the thickened layer forms the central film portion with the thickened layer, and the remaining portion forms the thinned portion.

[0010] In a preferred embodiment, the film body is a PET film, a PI film, a PVDF film, or a PTFE film, and / or the Young's modulus of the thickened layer is greater than 10 GPa, and / or the thickened layer is one of a steel layer, an aluminum layer, a copper layer, or a glass layer with a Young's modulus greater than 10 GPa, and / or the thickness of the thickened layer is 10% to 215% of the thickness of the film body, and / or the thickness of the film body is 1 μm to 1 mm.

[0011] On the other hand, this utility model proposes an electrostatic ultrasonic transducer, including the aforementioned diaphragm.

[0012] In a preferred embodiment, the electrostatic ultrasonic transducer further includes a top electrode, a bottom electrode, and a support structure. The top electrode is disposed on the diaphragm or is directly part of the diaphragm. The support structure is located between the diaphragm and the bottom electrode and is used to form an air gap between the diaphragm and the bottom electrode for the diaphragm to vibrate. A DC bias voltage and an AC voltage are connected between the top electrode and the bottom electrode, and the diaphragm vibrates and produces sound under the action of the AC voltage.

[0013] In a preferred embodiment, the support structure consists of a plurality of insulating protrusions arranged in an array, which divide the electrostatic ultrasonic transducer into a plurality of vibration units arranged in an array.

[0014] In a preferred embodiment, the electrostatic ultrasonic transducer further includes a fixed base plate and an insulating layer, the bottom electrode is disposed on the fixed base plate, and the insulating layer is located between the top electrode and the bottom electrode.

[0015] On the other hand, this utility model proposes an electronic device, including the above-mentioned electrostatic ultrasonic transducer.

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

[0017] This invention optimizes the structural design of the electrostatic thin-film ultrasonic transducer. Specifically, by adjusting the design of the diaphragm, the stiffness of the diaphragm near the support column is much lower than that of the diaphragm at the center. This concentrates the deformation of the diaphragm mainly at the edge of the diaphragm, while most of the diaphragm undergoes piston-like motion. This increases the effective vibration area ratio of the diaphragm and thus improves the sound pressure level of the electrostatic thin-film ultrasonic transducer. Attached Figure Description

[0018] Figure 1 A schematic diagram of an existing electrostatic ultrasonic transducer.

[0019] Figure 2 This is a schematic diagram of the diaphragm of an electrostatic ultrasonic transducer in one embodiment of the present invention;

[0020] Figure 3a and 3b These are schematic diagrams showing the structure of the thickened layer of the diaphragm located on the upper and lower surfaces of the thin film body in another embodiment of this utility model.

[0021] Figure 4 This is a schematic diagram of the electrostatic ultrasonic transducer in Embodiment 1 of this utility model;

[0022] Figure 5 This is a schematic diagram of the electrostatic ultrasonic transducer in Embodiment 2 of this utility model;

[0023] Figure 6 This is a schematic diagram of the electrostatic ultrasonic transducer in Embodiment 3 of this utility model;

[0024] Figure 7 This is a schematic diagram of the electrostatic ultrasonic transducer in Embodiment 4 of this utility model;

[0025] Figure 8 For the existing Figure 1 A simulation diagram of the diaphragm vibration in the structure shown.

[0026] Figure 9 This is a simulation diagram of the diaphragm vibration in the structure shown in Embodiment 1 of this utility model;

[0027] Figure 10 This is a simulation diagram of the diaphragm vibration in the structure shown in Embodiment 2 of this utility model.

[0028] The attached figures are labeled as follows:

[0029] 1. Diaphragm; 11. Central diaphragm section; 12. Thinning section; 13. Thin film body; 14. Thickening layer; 2. Top electrode; 3. Bottom electrode; 4. Support structure; 5. Air gap; 6. Fixed base plate; 7. Insulating layer. Detailed Implementation

[0030] The specific embodiments of this utility model are described in detail below, but it should be understood that the protection scope of this utility model is not limited to the specific embodiments.

[0031] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0032] like Figure 2 As shown, the diaphragm 1 of an electrostatic ultrasonic transducer disclosed in this utility model includes a central diaphragm portion 11 and a thinning portion 12. The thinning portion 12 is located at the edge of the central diaphragm portion 11 and its thickness is less than that of the central diaphragm portion 11. During operation, part of the position of the thinning portion 12 is fixed, and the remaining part vibrates and produces sound as a whole with the central diaphragm portion 11.

[0033] In practice, the thickness of the thinned portion 12 is preferably 1% to 20% of the thickness of the central membrane portion 11. The thickness of the central membrane portion 11 is generally 1µm to 1mm. That is, if the thickness of the central membrane portion 11 is 100µm, the thickness of the thinned portion 12 can be 1µm to 20µm, such as 5µm. The area of ​​the thinned portion is preferably 1% to 10% of the area of ​​the entire diaphragm.

[0034] In practice, the central film portion 11 and the thinned portion 12 can be integrally formed from a single film. That is, the thinned portion 12 can be formed by thinning the edges of the film, meaning that the central film portion 11 and the thinned portion 12 are made of the same material. In practice, the film can be any one of the following materials: PET film, PI film, PVDF film, PTFE film, etc.

[0035] like Figure 3a and 3bAs shown, in another alternative embodiment, the diaphragm 1 includes a separate thin film body 13 and a thickening layer 14. In implementation, the thickening layer 14 can be located in the middle of the upper surface and / or the middle of the lower surface of the thin film body 13. That is, this solution thickens the middle position of the original thin film body 13 by adding the thickening layer 14. The portion of the thin film body 13 corresponding to the thickening layer 14 combines with the thickening layer 14 to form the aforementioned central film portion 11, while the remaining portion of the thin film body 13 forms the aforementioned thinning portion 12. In this embodiment, the thickening layer 14 and the thin film body 13 can be made of the same or different materials, preferably different. In implementation, similar to the aforementioned film material, the thin film body 13 in this solution can also be any one of materials such as PET film, PI film, PVDF film, PTFE film, etc. The thickening layer 14 is preferably made of a material with a Young's modulus greater than 10 GPa, such as any one of steel, aluminum, copper, or glass layers with a Young's modulus greater than 10 GPa. Furthermore, in this embodiment, the thickness of the thickened layer 14 is preferably 10% to 215% of the thickness of the film body 13, so that the stiffness of the thickened portion is much greater than that of the film body 13, such as more than 10 times. Since stiffness is proportional to Young's modulus × thickness^3, if the Young's modulus of the film body 13 is 1 GPa and the thickness is 10 μm, then the thickened layer 14 can be made of a material with a Young's modulus > 10 GPa and a thickness > 10 μm, or a material with a Young's modulus > 100 GPa and a thickness > 5 μm. When the thickness of the thickened layer 14 is greater than 215% of the thickness of the film body 13, the solution of locally thinning the diaphragm (i.e., Example 1) is more suitable.

[0036] The thickness of the thin film body 13 is generally set to 1µm to 1mm. For example, if the thickness of the thin film body 13 is 100µm, the thickness of the thickened layer 14 can be 10µm to 200µm, such as 100µm.

[0037] Combination Figures 4-7 As shown, the electrostatic ultrasonic transducer disclosed in this utility model includes the aforementioned diaphragm 1, top electrode 2, bottom electrode 3, and support structure 4. The top electrode 2 is disposed on the diaphragm 1 or is directly part of the diaphragm 1. The support structure 4 is located between the diaphragm 1 and the bottom electrode 3, and is used to form an air gap 5 between the diaphragm 1 and the bottom electrode 3 for vibration of the diaphragm 1. A DC bias voltage Vdc and an AC voltage Vac are connected between the top electrode 2 and the bottom electrode 3. The diaphragm 1 vibrates and produces sound under the action of the AC voltage Vac.

[0038] Preferably, the support structure 4 consists of multiple insulating protrusions arranged in an array, which divide the electrostatic ultrasonic transducer into multiple vibrating units arranged in an array. Except for the portion of the diaphragm 1 that is in contact with the support structure 4 and does not vibrate to produce sound, the rest of the diaphragm 1 undergoes piston-like motion, i.e., all of them vibrate to produce sound.

[0039] Furthermore, the electrostatic ultrasonic transducer also includes a fixed base plate 6 and an insulating layer 7, wherein the bottom electrode 3 is disposed on the fixed base plate 6, and the insulating layer 7 is located between the top electrode 2 and the bottom electrode 3 for insulation between the two electrodes to prevent short circuit.

[0040] Different structures of the diaphragm 1 result in different structures of the electrostatic ultrasonic transducer. The following describes the structure of the electrostatic ultrasonic transducer of this invention using several specific embodiments.

[0041] Example 1

[0042] like Figure 4 As shown in Embodiment 1, an electrostatic ultrasonic transducer includes a diaphragm 1, a top electrode 2, a fixed base plate 6, a bottom electrode 3, an insulating layer 7, and a support structure 4. In this embodiment, the diaphragm 1 includes a central membrane portion 11 and a thinning portion 12, both integrally formed from a single thin film. The thinning portion 12 is located at the edge of the central membrane portion 11, and its thickness is less than that of the central membrane portion 11. In this embodiment, the thin film 1 is specifically a PET film with a diameter of 2 mm. The thickness of the central membrane portion 11 is 100 μm, and the thickness of the thinning portion 12 is 5 μm with a width of 0.15 mm.

[0043] The top electrode 2 is disposed on the lower surface of the diaphragm 1, and its position corresponds to the position of the central diaphragm 11, that is, the top electrode 2 completely covers the central diaphragm 11.

[0044] The bottom electrode 3 is disposed on the upper surface of the fixed base plate 6, and the insulating layer 7 is disposed on the upper surface of the bottom electrode 3.

[0045] The support structure 4 is located between the thinned portion 12 of the diaphragm 1 and the insulating layer 7, and is used to form an air gap 5 between the diaphragm 1 and the insulating layer 7. In this embodiment, the support structure 4 consists of multiple insulating protrusions, such as one insulating protrusion at each apex of the thinned portion 12.

[0046] During operation, a DC bias voltage Vdc and an AC voltage Vac are applied between the top electrode 2 and the bottom electrode 3. The diaphragm 1 vibrates and produces sound under the action of the AC voltage Vac. Except for the part of the thinned portion 12 of the diaphragm 1 that does not vibrate and produce sound in contact with the insulating protrusion, the rest of the portion vibrates and produces sound together with the central diaphragm portion 11.

[0047] like Figure 8 As shown, this is the existing Figure 1 The diagram shown illustrates the vibration of diaphragm 1 under the same conditions as in Example 1, before the edge of diaphragm 1 is thinned. Figure 9The figures shown are simulation diagrams of the diaphragm vibration in Embodiment 1. The vertical axis of both figures represents the displacement of the diaphragm surface, in μm. A comparison of these two figures clearly shows that the deformation of the diaphragm in Embodiment 1 is mainly concentrated in the thinned portion 12, i.e., the edge of the film. The central portion 11 of the diaphragm essentially undergoes piston-like motion, meaning its effective vibration area is much larger than that of existing diaphragms. According to the formula: Effective vibration area S of the diaphragm = Average displacement of the membrane surface / Displacement of the membrane center point × St, where St is the total area of ​​the diaphragm, and the effective vibration area ratio is S / St. The sound pressure P of the electrostatic ultrasonic transducer is proportional to the effective vibration area S of the diaphragm. According to the sound pressure level formula: SPL = 20 × log10(P / Pref), where Pref is the reference sound pressure, which is 2e-5 Pa. Therefore, as the effective vibration area S of the diaphragm increases, the sound pressure level of the corresponding electrostatic ultrasonic transducer also increases overall. In Embodiment 1, the effective vibration area ratio of the diaphragm increases from 53% to 91%, resulting in a corresponding increase of 4.7 dB in the sound pressure level.

[0048] Example 2

[0049] like Figure 5 As shown, unlike Embodiment 1, the electrostatic ultrasonic transducer disclosed in Embodiment 2 has a diaphragm 1 comprising a separate thin film body 13 and a thickened layer 14. The thickened layer 14 is located in the middle of the upper surface of the thin film body 13. A portion of the thin film body 13 corresponding to the thickened layer 14 forms a central membrane portion 11, and the remaining portion forms a thinned portion 12. In Embodiment 2, the thin film body 13 is a PET film with a diameter of 2 mm and a thickness of 100 μm, and the thickened layer 14 is a steel sheet with a diameter of 1.7 mm and a thickness of 100 μm. Furthermore, in Embodiment 2, the top electrode 2 completely covers the lower end face of the thin film body 13.

[0050] The structure of the rest of Example 2 is the same as that in Example 1, and will not be described again here.

[0051] like Figure 10 The figure shown is a simulation diagram of the diaphragm vibration in Embodiment 2. This diagram, along with the above... Figure 8 The comparison clearly shows that the effective vibration area of ​​the diaphragm in this embodiment 2 is larger than that of the existing diaphragm. In this embodiment 2, the proportion of the effective vibration area of ​​the diaphragm is increased from 53% to 78%, and the sound pressure level is correspondingly increased by 3.4 dB.

[0052] Example 3

[0053] like Figure 6As shown, the electrostatic ultrasonic transducer disclosed in Embodiment 3 also includes a diaphragm 1 comprising a separate thin film body 13 and a thickened layer 14. Unlike Embodiment 2, in Embodiment 3, the thickened layer 14 is located in the middle of the lower surface of the thin film body 13. The portion of the thin film body 13 corresponding to the thickened layer 14 forms a central film portion 11, while the remaining portion forms a thinned portion 12. Furthermore, in Embodiment 3, the top electrode 2 completely covers the lower end face of the thickened layer 14.

[0054] The structure of the rest of Example 3 is the same as that in Example 2, and will not be described again here.

[0055] Example 4

[0056] like Figure 7 As shown, the electrostatic ultrasonic transducer disclosed in this embodiment 4 also includes a separate thin film body 13 and a thickened layer 14 in its diaphragm 1. Unlike embodiment 3, since the thickened layer 14 itself is conductive, the top electrode 2 is omitted in this embodiment, that is, the thickened layer 14 is directly used as the top electrode.

[0057] The structure of the rest of Example 4 is the same as that in Example 3, and will not be described again here.

[0058] This utility model also discloses an electronic device, including the aforementioned electrostatic thin-film ultrasonic transducer. In practice, the electronic device can be, but is not limited to, a laptop, mobile phone, automobile, or other electronic devices with a display screen. Furthermore, when combined with these electronic devices, the aforementioned electrostatic thin-film ultrasonic transducer can be directly attached to the display screen of the electronic device or integrated within the display screen to achieve directional sound emission from the screen.

[0059] The advantage of this invention is that by optimizing the structural design of the electrostatic thin-film ultrasonic transducer, specifically by adjusting the design of the diaphragm, the stiffness of the diaphragm near the support column is much lower than that of the diaphragm at the center. This concentrates the deformation of the diaphragm mainly at the edge of the diaphragm, while most of the diaphragm undergoes piston-like motion, thereby increasing the effective vibration area ratio of the diaphragm and thus improving the sound pressure level of the electrostatic thin-film ultrasonic transducer.

[0060] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the present invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the present invention, as well as various different choices and variations. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A diaphragm for an electrostatic ultrasonic transducer, characterized in that, The diaphragm includes a central diaphragm portion and a thinned portion. The thinned portion is located at the edge of the central diaphragm portion and its thickness is less than that of the central diaphragm portion. Part of the thinned portion is fixed, and the remaining part vibrates and produces sound as a whole with the central diaphragm portion.

2. The diaphragm of an electrostatic ultrasonic transducer as described in claim 1, characterized in that, The central membrane portion and the thinning portion are integrally formed from a single thin film.

3. The diaphragm of an electrostatic ultrasonic transducer as described in claim 2, characterized in that, The film is a PET film, a PI film, a PVDF film, or a PTFE film, and / or the thickness of the thinned portion is 1% to 20% of the thickness of the central film portion, and / or the area of ​​the thinned portion is 1% to 10% of the area of ​​the entire diaphragm, and / or the thickness of the central film portion is 1µm to 1mm.

4. The diaphragm of an electrostatic ultrasonic transducer as described in claim 1, characterized in that, The diaphragm includes a separate thin film body and a thickened layer. The thickened layer is located in the middle of the upper surface and / or lower surface of the thin film body. The portion of the thin film body corresponding to the thickened layer forms the central film portion, and the remaining portion forms the thinned portion.

5. The diaphragm of an electrostatic ultrasonic transducer as described in claim 4, characterized in that, The film body is a PET film, PI film, PVDF film, or PTFE film, and / or the Young's modulus of the thickened layer is greater than 10 GPa, and / or the thickened layer is one of a steel layer, aluminum layer, copper layer, or glass layer with a Young's modulus greater than 10 GPa, and / or the thickness of the thickened layer is 10% to 215% of the thickness of the film body, and / or the thickness of the film body is 1 μm to 1 mm.

6. An electrostatic ultrasonic transducer, characterized in that, The diaphragm of the electrostatic ultrasonic transducer as described in any one of claims 1 to 5.

7. An electrostatic ultrasonic transducer as described in claim 6, characterized in that, The electrostatic ultrasonic transducer also includes a top electrode, a bottom electrode, and a support structure. The top electrode is disposed on the diaphragm or is directly part of the diaphragm. The support structure is located between the diaphragm and the bottom electrode and is used to form an air gap between the diaphragm and the bottom electrode to provide air for the diaphragm to vibrate. A DC bias voltage and an AC voltage are connected between the top electrode and the bottom electrode. The diaphragm vibrates and produces sound under the action of the AC voltage.

8. An electrostatic ultrasonic transducer as described in claim 7, characterized in that, The support structure consists of multiple insulating protrusions arranged in an array, which divide the electrostatic ultrasonic transducer into multiple vibration units arranged in an array.

9. An electrostatic ultrasonic transducer as described in claim 7, characterized in that, The electrostatic ultrasonic transducer also includes a fixed base plate and an insulating layer, with the bottom electrode disposed on the fixed base plate and the insulating layer located between the top electrode and the bottom electrode.

10. An electronic device, characterized in that, Includes the electrostatic ultrasonic transducer as described in any one of claims 6 to 9.

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