Electrostatic Transducer Spacer Membrane Tension
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Solution Overview
Problem
Existing electrostatic loudspeakers face challenges in achieving sufficient membrane displacement and acoustic performance, with previous designs not fully optimizing the tension and movement of the membrane to enhance sound quality and frequency range.
Innovation Solution
The design incorporates a spacer member with optimally sized and shaped holes that create a 'drum-skin' effect, providing a return spring mechanism through membrane tension, allowing for improved acoustic performance by increasing the usable frequency range and sound quality, with specific hole dimensions and patterns enhancing tension and vibration areas.
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 and AC signal, then electrostatic force is exerted on the charged membrane to drive air, but sufficient displacement of the membrane is not achieved
Solution Approach 1:
The patent divides the membrane into multiple segments by introducing a spacer member with holes between the backplate and diaphragm. This segmentation allows different portions of the membrane to move independently, increasing overall displacement capability while maintaining electrostatic force application.
Solution Approach 2:
The spacer member creates local variations in the membrane structure by introducing holes at specific locations. This allows certain regions of the membrane to have greater freedom of movement while other regions maintain structural integrity, optimizing both displacement and force transmission.
2Length 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 greater displacement of the second and third layers is achieved, but device complexity increases
Solution Approach 1:
The spacer member serves multiple functions simultaneously: it provides the necessary spacing for membrane displacement, creates the hole pattern for segmentation, and maintains structural alignment between layers. This multi-functionality reduces overall device complexity despite adding displacement capability.
Solution Approach 2:
The spacer member acts as an intermediary element between the rigid backplate and the flexible diaphragm. It mediates the interaction between these two components, providing the necessary mechanical support while allowing sufficient freedom of movement, thus simplifying the overall structural design.
3Reliability
If the holes in the spacer member have optimal dimensions and shapes, then the drum-skin effect is enhanced and acoustic performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies optimal parameter ranges for the holes (dimensions between 1-50mm, aspect ratio less than 1.5) rather than exact values. This approach allows for manufacturing tolerances while still achieving the desired drum-skin effect and acoustic performance, balancing reliability with manufacturability.
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
This configuration results in a 6dB increase in sound pressure level between 200Hz and 5kHz, demonstrating improved acoustic performance and sound quality, while allowing for efficient membrane movement and reduced risk of membrane damage.
Implementation Method 1
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
When an AC signal is applied, the drum skins resonate, and parts of that conducting layer vibrate to produce the required sound.
Implementation Method 3
The holes provided in the spacer member cooperate with the membrane to provide an array of regions where a 'drum-skin' effect is produced. The ratio between the maximum and minimum lateral dimensions may be less than 1.5 e.g. less than 1.2.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An electrostatic transducer (100) comprises an electrically conductive backplane member (102) having an array of through apertures (112); a spacer member (104) disposed over the backplane member (102), the spacer member (104) having an array of holes (114) therethrough, the holes (114) each having a maximum lateral dimension less than twice a minimum lateral dimension; and a flexible electrically conductive membrane (106) disposed over the spacer member (104). The transducer (100) is arranged in use to apply an electrical potential which gives rise to an attractive electrostatic force between the backplane member (102) and the membrane (106) thereby moving portions of the membrane (106) spanning said holes in the spacer member (104) towards said backplane member (102).