Electrostatic ultrasonic transducer and electronic device

Abstract

The utility model discloses an electrostatic ultrasonic transducer and electronic equipment, the electrostatic ultrasonic transducer includes vibration layer and with vibration layer phase frame adhesion's base material layer, and the air gap is formed between vibration layer and base material layer, and vibration layer vibrates and sounds under the action of loaded drive voltage, vibration layer includes vibration layer subassembly and top electrode, and vibration layer subassembly includes diaphragm and mass block, and mass block sets up on the top surface of diaphragm far from base material layer, and top electrode sets up on the bottom surface of diaphragm close to base material layer. The utility model discloses through increasing a mass block on diaphragm, realizes its close ideal piston's vibration mode to improve the output sound pressure and electromechanical conversion efficiency of device significantly under the condition of keeping target resonant frequency unchanged.

Description

Technical Field

[0001] This utility model relates to the field of ultrasonic transducer technology, specifically to an electrostatic ultrasonic transducer and electronic equipment. 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] Common electrostatic thin-film ultrasonic transducer structures are generally as follows: Figure 1 As shown, the structure, from top to bottom, includes a thin film, a top electrode, a support pillar, an insulating layer, a bottom electrode, and a fixed base plate, with an air gap between the top electrode and the insulating layer. A DC bias voltage Vdc and an AC voltage Vac are applied between the top and bottom electrodes to drive the thin film to vibrate and produce sound.

[0004] However, conventional electrostatic ultrasonic transducer units typically use thin films of uniform thickness, and their vibration mode is not an ideal piston vibration. Their effective vibration area ratio is low, which limits the sound energy conversion efficiency. Utility Model Content

[0005] The purpose of this invention is to provide an electrostatic ultrasonic transducer and electronic device that can enhance the output sound pressure.

[0006] To achieve the above objectives, this utility model proposes an electrostatic ultrasonic transducer, comprising a vibrating layer and a substrate layer that is adjacent to the vibrating layer. An air gap is formed between the vibrating layer and the substrate layer. The vibrating layer vibrates and generates sound under the action of an applied driving voltage. The vibrating layer includes a vibrating layer assembly and a top electrode. The vibrating layer assembly includes a diaphragm and a mass block. The mass block is disposed on the top surface of the diaphragm away from the substrate layer, and the top electrode is disposed on the bottom surface of the diaphragm near the substrate layer.

[0007] In a preferred embodiment, the mass block coincides with the center of the diaphragm, and the mass block completely or partially covers the top surface of the diaphragm.

[0008] In a preferred embodiment, the radius ratio or side length ratio of the mass block to the diaphragm is 0.5 to 0.9.

[0009] In a preferred embodiment, the material of the mass block may be the same as or different from the material of the diaphragm.

[0010] In a preferred embodiment, both the mass block and the diaphragm are PET layers, PI layers, or silicon layers, or the diaphragm is a PET layer, PI layer, or silicon layer, and the mass block is a metal layer or a glass layer.

[0011] In a preferred embodiment, the radius ratio or side length ratio of the mass block to the diaphragm is 0.7.

[0012] In a preferred embodiment, the transducer further includes a support structure disposed between the top electrode and the substrate layer for forming the air gap between the top electrode and the substrate layer.

[0013] In a preferred embodiment, the substrate layer includes a fixed substrate layer, a bottom electrode, and an insulating layer. The bottom electrode is disposed on the top surface of the fixed substrate layer near the vibration layer, the insulating layer is disposed on the top surface of the bottom electrode near the vibration layer, and the support structure is located between the insulating layer and the top electrode.

[0014] In a preferred embodiment, a driving voltage is applied between the top electrode and the bottom electrode, the driving voltage including an AC driving voltage or a combination of a DC bias voltage and an AC driving voltage.

[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] 1. This utility model achieves a vibration mode of the electrostatic ultrasonic transducer that is closer to that of an ideal piston by adding a mass block to the diaphragm, thereby increasing its effective vibration area and enabling more effective energy radiation into the medium, thus significantly improving the surface acoustic pressure and electromechanical conversion efficiency. Moreover, the structure is simple and easy to implement.

[0018] 2. By adding a mass block to the diaphragm, this utility model significantly improves the overall stiffness of the diaphragm, enabling the device to withstand higher driving voltages without collapsing, thus improving the device's voltage resistance. This provides a prerequisite for achieving high sound pressure output.

[0019] 3. By setting the radius and thickness of the mass block, this utility model can accurately control the resonant frequency of the device at the target value while increasing the sound pressure, thus meeting the needs of different application scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an existing electrostatic ultrasonic transducer;

[0021] Figure 2 This is a schematic diagram of the electrostatic ultrasonic transducer of this utility model;

[0022] Figure 3 This is a simulation diagram showing the ratio of the mass block to the diaphragm radius and the maximum sound pressure level on the diaphragm surface in one embodiment of this utility model.

[0023] The attached figures are labeled as follows:

[0024] 1. Vibrating layer, 11. Top electrode, 12. Diaphragm, 13. Mass block, 2. Support structure, 3. Substrate layer, 31. Fixed substrate layer, 32. Bottom electrode, 33. Insulating layer, 4. Air gap. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] like Figure 2 As shown, the electrostatic ultrasonic transducer disclosed in this utility model includes a vibrating layer 1 and a substrate layer 3 that is attached to the vibrating layer 1. An air gap 4 is formed between the vibrating layer 1 and the substrate layer 3. During operation, a driving voltage is applied between the vibrating layer 1 and the substrate layer 3. The changing electrostatic force drives the vibrating layer 1 to generate high-frequency vibration. The radiated ultrasonic waves are nonlinearly demodulated in the air to form audible directional sound.

[0028] Preferably, the vibration layer 1 includes a vibration layer assembly and a top electrode 11. The vibration layer assembly includes a diaphragm 12 and a mass block 13. The mass block 13 is disposed on the top surface of the diaphragm 12 away from the substrate layer 3, and the top electrode 11 is disposed on the bottom surface of the diaphragm 12 close to the substrate layer 3. That is, the mass block 13 and the top electrode 11 are respectively located on the upper and lower end surfaces of the diaphragm 12.

[0029] In implementation, the mass block 13 is preferably located in the middle of the diaphragm 12, and its center preferably coincides with the center of the diaphragm 12. The mass block 13 can completely or partially cover the top surface of the diaphragm 12, preferably located in the middle and partially covering the top surface. The addition of the mass block 13 significantly increases the stiffness of the central portion of the diaphragm 12 (i.e., the portion covered by the mass block 13). Under electric field drive, this portion tends to translate rather than bend, while the edge portion of the diaphragm 12 acts as an elastic hinge. This structure makes the vibration mode of the entire diaphragm 12 closer to the ideal rigid piston vibration, increasing the effective vibration area of ​​the diaphragm 12 and more effectively radiating energy into the medium, thereby significantly increasing the surface acoustic pressure. Furthermore, by adding the mass block 13, the overall stiffness of the diaphragm 12 can be significantly improved. According to the mechanical model, higher stiffness means that the device can withstand higher driving voltages without collapsing, which provides a prerequisite for achieving high sound pressure output.

[0030] Furthermore, in practice, the material of the mass block 13 can be the same as or different from that of the diaphragm 12. If they are the same, both the mass block 13 and the diaphragm 12 can be PET (Polyethylene terephthalate) layers, PI (Polyimide) layers, or silicon layers. If they are different, the diaphragm 12 can be a PET layer, a PI layer, or a silicon layer, while the mass block 13 can be other high-density materials, such as a metal layer (which can be aluminum, steel, copper, etc.) or a glass layer.

[0031] Adding mass block 13 alters the equivalent mass and equivalent stiffness of diaphragm 12, thus affecting its resonant frequency. The radius or side length of mass block 13 and its thickness are key parameters influencing the device's output sound pressure level and electromechanical conversion efficiency while maintaining the target resonant frequency. In practice, an optimal ratio range between the radius / side length of mass block 13 and the radius / side length of diaphragm 12 can be determined through finite element simulation analysis. After determining the optimal range for the radius / side length ratio, the thickness of mass block 13 is gradually increased until the resonant frequency of the entire vibrating layer assembly (diaphragm 12 + mass block 13) returns to the initially designed target resonant frequency.

[0032] Preferably, the radius ratio or side length ratio of the mass block 13 to the diaphragm 12 is in the range of 0.5 to 0.9, with 0.7 being the optimal value.

[0033] The substrate layer 3 specifically includes a fixed substrate layer 31, a bottom electrode 32, and an insulating layer 33. The bottom electrode 32 is disposed on the top surface of the fixed substrate layer 31 near the vibrating layer 1, and the insulating layer 33 is disposed on the upper end surface of the bottom electrode 32 near the vibrating layer 1. In practice, the fixed substrate layer 31 can be a glass substrate, and the bottom electrode 32 can be an ITO (indium tin oxide) layer. The insulating layer 33 can be made of OC (photoresist), printing ink, or SiN... x It can be achieved using silicon nitride, SiOx (silicon oxide), PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PI (polyimide) or Parylene (poly(p-xylene)).

[0034] In addition, a support structure 2 is provided between the vibrating layer 1 and the substrate layer 3, so that an air gap 4 is formed between the vibrating layer 1 and the substrate layer 3 to allow the vibrating layer 1 to vibrate vertically. In practice, the support structure 2 can be formed on the vibrating layer 1 or on the substrate layer 3, preferably on the substrate layer 3, specifically on the upper surface of the insulating layer 33 near the vibrating layer 1. The support structure 2 can be implemented as an array of support points / columns with a certain thickness, and its material can be selected from OC adhesive, printing ink, SiN... x SiOx Materials include PTFE, PVDF, PI, or SU-8 photoresist. Furthermore, the height of the support structure 2 and the spacing between adjacent support structures 2 can be determined according to actual acoustic requirements and are not limited here.

[0035] During operation, a driving voltage is applied between the top electrode 11 of the vibration layer 1 and the bottom electrode 32 of the substrate layer 3. The driving voltage can be an AC voltage Vac or a combination of a DC bias voltage Vdc and an AC voltage Vac. The changing electrostatic force drives the vibration layer 1 to generate high-frequency vibration. The radiated ultrasonic waves are nonlinearly demodulated in the air to form audible directional sound.

[0036] On the other hand, this utility model also proposes an electronic device, including the aforementioned electrostatic ultrasonic transducer. In practice, the electronic device can be a display or other similar device. When integrated with the electrostatic ultrasonic transducer, the electrostatic ultrasonic transducer can be directly mounted externally, attached to the display, or integrated into the display.

[0037] In one specific embodiment, an electrostatic ultrasonic transducer with a target resonant frequency of 40kHz is designed as an example. In this embodiment, the diaphragm 12 is a PI layer with a thickness of 200µm and a diameter of 3.4mm; the mass block 13 is made of the same material as the diaphragm 12, which is a PI layer; the top electrode and the bottom electrode are both 80nm thick ITO layers, the insulating layer is a 10µm thick OC layer, the fixing substrate layer is a 1mm thick glass; and the support structure 2 has a height of 10µm.

[0038] A combination of a DC bias voltage of 300V and an AC voltage of 100V was applied between the top electrode 11 of the vibrating layer 1 and the bottom electrode 32 of the substrate layer 3. The ratio of the radius of the mass block 13 to the radius of the diaphragm 12 was scanned within a range from 50% to 90%, while adjusting the thickness of the mass block 13 to maintain the resonant frequency at 40kHz for each calculation. The surface output sound pressure level of the ultrasonic transducer was calculated and recorded for each radius ratio, as shown below. Figure 3 As shown in the figure, when the ratio of the radius of mass block 13 to the radius of the diaphragm reaches 70%, the output sound pressure reaches a relatively high level and tends to stabilize. Therefore, 70% (i.e., a diameter of 2.38 mm) is selected as the optimal radius ratio, at which point the thickness of mass block 13 is 100 μm.

[0039] The advantages of this invention are as follows: 1. By adding a mass block to the diaphragm, this invention achieves a vibration mode for the electrostatic ultrasonic transducer that more closely resembles an ideal piston, increasing its effective vibration area and enabling more efficient energy radiation into the medium. This significantly improves surface acoustic pressure and electromechanical conversion efficiency, while maintaining a simple structure and ease of implementation. 2. By adding a mass block to the diaphragm, this invention significantly improves the overall stiffness of the diaphragm, allowing the device to withstand higher driving voltages without collapse, thus enhancing its voltage resistance and providing a prerequisite for achieving high sound pressure output. 3. Through precise setting of the radius and thickness of the mass block, this invention can accurately control the resonant frequency of the device to the target value while increasing sound pressure, meeting the needs of different application scenarios.

[0040] 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. An electrostatic ultrasonic transducer, characterized in that, The device includes a vibrating layer and a substrate layer that is attached to the vibrating layer. An air gap is formed between the vibrating layer and the substrate layer. The vibrating layer vibrates and produces sound under the action of an applied driving voltage. The vibrating layer includes a vibrating layer assembly and a top electrode. The vibrating layer assembly includes a diaphragm and a mass block. The mass block is disposed on the top surface of the diaphragm away from the substrate layer, and the top electrode is disposed on the bottom surface of the diaphragm near the substrate layer.

2. The electrostatic ultrasonic transducer as described in claim 1, characterized in that, The mass block coincides with the center of the diaphragm, and the mass block completely or partially covers the top surface of the diaphragm.

3. An electrostatic ultrasonic transducer as described in claim 1 or 2, characterized in that, The radius ratio or side length ratio of the mass block to the diaphragm is 0.5 to 0.

9.

4. The electrostatic ultrasonic transducer as described in claim 1, characterized in that, The material of the mass block may be the same as or different from the material of the diaphragm.

5. The electrostatic ultrasonic transducer as described in claim 4, characterized in that, Both the mass block and the diaphragm are PET, PI, or silicon layers, or the diaphragm is a PET, PI, or silicon layer and the mass block is a metal or glass layer.

6. The electrostatic ultrasonic transducer as described in claim 3, characterized in that, The ratio of the radius or the side length of the mass block to the diaphragm is 0.

7.

7. An electrostatic ultrasonic transducer as described in claim 1, characterized in that, The transducer also includes a support structure disposed between the top electrode and the substrate layer, for forming the air gap between the top electrode and the substrate layer.

8. An electrostatic ultrasonic transducer as described in claim 7, characterized in that, The substrate layer includes a fixed substrate layer, a bottom electrode, and an insulating layer. The bottom electrode is disposed on the top surface of the fixed substrate layer near the vibration layer, and the insulating layer is disposed on the top surface of the bottom electrode near the vibration layer. The support structure is located between the insulating layer and the top electrode.

9. An electrostatic ultrasonic transducer as described in claim 8, characterized in that, A driving voltage is applied between the top electrode and the bottom electrode. The driving voltage includes an AC driving voltage or a combination of a DC bias voltage and an AC driving voltage.

10. An electronic device, characterized in that, Includes the electrostatic ultrasonic transducer as described in any one of claims 1 to 9.

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