Active Vibration Noise Cancellation in Microphone Signals
Solution Overview
Problem
Microphones in electronic devices are prone to detecting unwanted structural vibration noise, which existing mechanical isolation methods fail to adequately address due to weight and design constraints.
Innovation Solution
An image capture device equipped with a microphone, a vibration sensor, and a processor that upsamples the vibration signal to determine correlation values and filter coefficients, allowing for the active reduction of mechanical noise in microphone signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical isolation devices such as dampeners are used to reduce unwanted structural vibration noise, then noise reduction is achieved, but device weight increases
Solution Approach 1:
The patent replaces mechanical isolation devices with an active noise cancellation system that uses a vibration sensor to detect structural vibrations and a processor to generate anti-noise signals that electronically cancel the unwanted noise in the microphone signal, eliminating the need for additional mechanical dampeners
Solution Approach 2:
The patent introduces a vibration sensor as an intermediary to detect structural vibrations and a processor as an intermediary to compute and apply noise cancellation, allowing noise reduction without direct mechanical contact or isolation structures
2Object-affected harmful factors
If mechanical isolation devices are used to reduce unwanted structural vibration noise, then noise reduction is achieved, but device design flexibility is limited
Solution Approach 1:
The patent replaces rigid mechanical isolation structures with a flexible electronic noise cancellation system that can be implemented through software algorithms, allowing designers greater freedom in device structure and configuration
Solution Approach 2:
The patent employs dynamic noise cancellation through adaptive filter coefficients that adjust in real-time based on detected vibrations, allowing the system to adapt to varying noise conditions without requiring fixed mechanical designs
3Device complexity
If vibration signal is sampled at a lower rate than microphone signal, then device complexity is reduced, but noise reduction effectiveness decreases
Solution Approach 1:
The patent performs preliminary upsample of the vibration signal to match the microphone signal sampling rate before processing, ensuring that the lower-cost vibration sensor data is brought to the necessary resolution for effective noise cancellation without requiring the sensor itself to operate at high sampling rates
Solution Approach 2:
The patent changes the sampling rate parameter of the vibration signal from its original lower rate to match the microphone signal rate through upsample operations, allowing the system to maintain noise reduction effectiveness while keeping the vibration sensor cost-effective
Data Source
AI summary
An integrated circuit includes a processor that upsamples a vibration signal. The processor determines a correlation value. The correlation value may be based on a microphone signal, the upsampled vibration signal, or both. The processor filters the vibration signal to remove a noise portion and obtain a processed microphone signal. The processor outputs the processed microphone signal.