Electrostatic Transducer Membrane Displacement and Sound Pressure
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Solution Overview
Problem
Existing electrostatic loudspeakers face challenges in achieving sufficient membrane displacement and improving acoustic performance.
Innovation Solution
An electrostatic transducer design featuring an electrically conductive first member with through apertures and a flexible, resiliently deformable second member that stores elastic potential energy, allowing for quicker restoration to equilibrium position when the electrical potential decreases, enhancing acoustic performance by increasing the usable frequency range and sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional electrostatic loudspeaker uses a conductive membrane between two perforated conductive backplates with high voltage DC bias, then sufficient electrostatic force is achieved, but the membrane displacement is insufficient and acoustic performance is limited
Solution Approach 1:
The transducer is divided into multiple functional layers: a first conductive layer with through apertures, a flexible insulating layer, and a second conductive layer. This segmentation allows each layer to perform its specific function optimally - the first layer provides electrostatic force generation, the insulating layer provides mechanical flexibility and electrical isolation, and the second layer serves as the movable diaphragm, collectively achieving both sufficient force and displacement
Solution Approach 2:
The patent employs a flexible insulating layer and a flexible conductive second layer that can deform and displace significantly. The flexible second layer acts as a thin film diaphragm that can move freely in response to electrostatic forces, achieving large displacement while maintaining structural integrity and electrical properties
2Use of energy by moving object
If the space between the backplate and membrane is reduced to about 0.1 mm, then a low voltage can push the membrane, but the membrane displacement remains insufficient
Solution Approach 1:
The patent introduces a flexible insulating layer as an intermediate dimension between the rigid first conductive layer and the flexible second layer. This additional dimensional element allows the system to achieve large displacement in the flexible layer while maintaining a compact overall structure, decoupling the voltage requirement from the displacement limitation
3Length of moving object
If spaces are provided between the first and second layers or between the second and third layers, then greater freedom of movement and displacement are achieved, but acoustic performance requires further improvement
Solution Approach 1:
The patent optimizes the physical and electrical parameters of each layer - the conductivity distribution, thickness, and material properties - to achieve the right balance between displacement capability and acoustic performance. By carefully controlling these parameters, the transducer achieves both large movement freedom and improved sound quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design results in a 6 dB increase in sound pressure level between 200 Hz and 5 kHz, improving the overall quality of sound generated by the transducer.
Implementation Method 1
A DC bias is applied to the membrane and an AC signal voltage is applied to the two backplates. Voltages of hundreds or even thousands of volts may be required. The signals cause an electrostatic force to be exerted on the charged membrane, which moves to drive the air on either side of it.
Implementation Method 2
at least one (104) of the one or more further members is resiliently deformable and is arranged in use to exert a resilient biasing force biasing said second member (106) back towards said equilibrium position when displaced therefrom by said electrical potential
Data Source
AI summary
An electrostatic transducer (100) comprises an electrically conductive first member (102) having an array of through apertures (112) and one or more further members (104, 106). The one or more further members (104, 106) include a flexible electrically conductive second member (106) arranged in use to be displaced from an equilibrium position towards the first member (102) by an electrostatic force in response to an electrical potential applied to one or both of the first member (102) and the second member (106). At least one (104) of the one or more further members is resiliently deformable and is arranged in use to exert a resilient biasing force biasing said second member (106) back towards said equilibrium position when displaced therefrom by said electrical potential.