Condenser Microphone Polar Pattern Adjustment via Dual Biasing
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Solution Overview
Problem
Condenser microphones with fixed electret biasing lack adjustable polar patterns, limiting their versatility, while external biasing methods often require external power sources, making them unsuitable for wireless and portable applications.
Innovation Solution
A condenser microphone design that combines electret and external biasing methods, allowing for continuous adjustment of polar patterns through superposition of signals from multiple capsules, enabling flexible and low-power operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electret biasing is used, then the microphone does not require an external power source, but the polar pattern cannot be adjusted
Solution Approach 1:
The patent combines electret biasing and external biasing methods into a single microphone capsule, allowing the backplate to have both electret material for baseline biasing and external voltage application capability for adjustable polar patterns. This merging enables continuous polar pattern adjustment while maintaining low power consumption characteristics of electret biasing.
Solution Approach 2:
The backplate is designed to serve multiple functions: it provides structural support, holds electret material for biasing, and accepts external voltage application for polar pattern adjustment. This multi-functionality allows the single backplate to enable both fixed and adjustable polar patterns without requiring separate biasing systems.
2Adaptability or versatility
If external biasing is used, then the polar pattern can be adjusted, but an external power source is required
Solution Approach 1:
The patent merges electret biasing and external biasing methods, allowing the microphone to use electret material for baseline biasing (reducing power needs) while still accepting external voltage application for polar pattern adjustment when needed.
Solution Approach 2:
The patent changes the bias voltage parameter continuously from fixed (electret only) to variable (electret + external), enabling polar pattern adjustment while maintaining the low-power advantage of electret biasing through superposition of voltage effects.
3Adaptability or versatility
If multiple microphone capsules are used to achieve different polar patterns, then polar pattern versatility is improved, but device complexity increases
Solution Approach 1:
The patent segments the biasing function from the capsule structure, allowing a single capsule to achieve multiple polar patterns through electrical control rather than requiring multiple physical capsules. This segmentation reduces structural complexity while maintaining pattern versatility.
Solution Approach 2:
The patent uses parameter changes (bias voltage adjustment) to achieve different polar patterns from a single capsule, replacing the need for multiple capsules with fixed patterns. This parameter-based control simplifies the device structure while providing continuous polar pattern adjustment capability.
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 combination of electret and external biasing provides a highly adjustable and low-power microphone with continuous variability in polar patterns, suitable for high-tier wireless handheld applications, enhancing versatility and performance.
Implementation Method 1
Electret materials are able to hold static electrical charge for long periods of time without an external supply
Implementation Method 2
Air pressure from sound waves striking the diaphragm causes the diaphragm to vibrate
Implementation Method 3
causes the diaphragm to vibrate
Implementation Method 4
changes the distance between the two plates, causing a change in the capacitance of the microphone. The dynamic change in capacitance is reflected in a dynamic change of voltage across the capacitor
Data Source
AI summary
A condenser microphone with at least two microphone capsules, each including a diaphragm and a backplate. The backplates of both the first capsule and second capsule having an electret bias. The first capsule having a first polar pattern, and the second capsule having a second polar pattern. The second capsule having an external voltage bias that is continuously variable over a certain voltage range. This external voltage bias can be applied to the second diaphragm or second backplate. The microphone's total polar pattern consists of a combination of the first polar pattern and the second polar pattern. Using the external voltage bias of the second capsule, the microphone's total polar pattern is continuously variable throughout a range set by the external voltage bias.