Capacitive Microphone Structure for Biological Sound Contact Noise Control
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Solution Overview
Problem
Existing biological sound detection devices with capacitive-type microphones generate significant noise signals when contacting a body surface, interfering with accurate diagnosis due to frequency bands exceeding 500 Hz, including noise from device contact and hand vibrations.
Innovation Solution
A biological sound detection device with a capacitive-type microphone is configured such that the vibrating membrane displaces away from the backplate upon contact, minimizing noise generation by setting the volume between the film and vibrating membrane to prevent contact and optimizing sensitivity for desired signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive-type microphone is used to detect biological sounds, then sensitivity to biological sounds is improved, but noise signals are generated when the device contacts the body surface
Solution Approach 1:
The patent changes the physical parameters of the microphone structure by setting a specific volume for the space between the film and vibrating membrane, and configuring the pressure transmission path through the backplate. These parameter changes ensure that the vibrating membrane displaces away from the backplate upon contact, preventing contact noise while maintaining biological sound detection sensitivity.
2Measurement precision
If the vibrating membrane is allowed to displace freely to maintain sensitivity, then biological sound signal level is improved, but contact noise signals increase
Solution Approach 1:
The patent inverts the conventional displacement direction by configuring the pressure transmission path so that pressure applied to the film passes through the backplate to the vibrating membrane, causing displacement away from the backplate. This inversion ensures that contact pressure produces displacement in the opposite direction, preventing the vibrating membrane from contacting the backplate and generating noise.
3Object-generated harmful factors
If operational switching is implemented to suppress noise, then noise signal level is reduced, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent implements a self-service solution where the microphone structure automatically prevents noise generation through its inherent design. The specific volume configuration and pressure transmission path ensure that upon contact, the vibrating membrane displaces away from the backplate, eliminating the need for operational switching or additional control mechanisms to suppress noise.
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
Suppresses noise signals while maintaining sensitivity for desired biological sound detection, allowing accurate signal conversion without cumbersome operational switching and reducing noise interference.
Implementation Method 1
a capacitive-type microphone that generates a biological sound signal from a change in capacitance between a vibrating membrane that vibrates depending on a magnitude of a biological sound
Implementation Method 2
a sound collecting space for a biological sound, a film covering an opening of the sound collecting space, a microphone that is arranged in a rear chamber communicating with the sound collecting space and converts the biological sound into a biological sound signal
Data Source
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AI summary
Provided is a biological sound detection device that can detect a desired biological sound signal while suppressing a signal level of a noise signal. The biological sound detection device (100) comprises a sound collecting space (3) for a biological sound, a film (8) covering an opening thereof, a microphone (2) arranged in a rear chamber communicating with the sound collecting space (3), and a signal processing section (7) that signal processes the biological sound signal. The microphone (2) is constituted of a capacitive-type microphone and arranged so that a pressure applied to the film (8) passes through a backplate and is applied to a vibrating membrane and a displacement of the vibrating membrane caused by the pressure is initiated from a displacement in a direction away from the backplate. A volume of a space between the film (8) and the vibrating membrane is set so that the vibrating membrane does not come into contact with the backplate when the vibrating membrane displaces in a direction approaching the backplate and the displacement of the vibrating membrane becomes a displacement that can convert the biological sound into the biological sound signal.