Passive Audio Kill Switch With Gradual PCB Shunting
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Solution Overview
Problem
Audible popping sounds occur when shunting an audio signal to ground using traditional mechanical on/off switches with metal contacts in live and recorded audio applications.
Innovation Solution
A passive audio 'kill' switch design featuring interlaced copper traces on a printed circuit board that gradually shunts the signal to ground over several milliseconds, using a conductive rubber button and a spring mechanism to prevent direct metal contact, ensuring noiseless signal cessation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical on/off switches with metal contacts are used to shunt audio signal to ground, then the switch can effectively stop the audio signal, but audible popping sounds are generated during signal cessation
Solution Approach 1:
The patent segments the ground connection path into multiple parallel traces (at least three) instead of using a single direct metal contact. This segmentation distributes the signal shunting action across multiple pathways, preventing the sudden complete short-circuit that causes popping sounds while maintaining effective signal cessation.
Solution Approach 2:
The patent introduces an intermediary conductive element (such as a conductive rubber button or flexible printed circuit) between the signal path and ground. This intermediary gradually establishes the ground connection through its material properties and contact mechanics, smoothing out the transition and eliminating the abrupt electrical change that generates audible pops.
2Device complexity
If direct metal to metal contacts are used in mechanical switches, then the switch structure is simple and reliable, but unwanted noise is produced during operation
Solution Approach 1:
The patent changes the physical parameters of the contact mechanism by using multiple parallel traces with finite width and spacing, rather than idealized zero-dimensional metal points. This parameter change creates a distributed contact area that gradually engages with the signal path, transforming the abrupt metal-to-metal contact into a smoother transition that reduces noise while maintaining structural simplicity.
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 solution effectively eliminates unwanted noise during live performances and recordings by incrementally shunting the audio signal to ground, maintaining a noiseless audio signal cessation.
Implementation Method 1
A printed circuit board containing a grounding ring on the bottom is joined to a lower metal housing, using a plurality of interlaced three mil copper traces from a center signal trace on top and outer grounding ring on bottom respectively
Implementation Method 2
A carbon impregnated conductive rubber button is joined to a spring, in order to apply back tension and keep the switch in the off position until engaged by the end user
Implementation Method 3
The three mil signal and ground traces are interlaced in a way to gradually shunt the signal to ground over several milliseconds, as downward pressure is applied to the conductive rubber button
Data Source
AI summary
An audio kill switch provides a noiseless passive cessation of an audio signal. A printed circuit board is joined to an upper shell and has a plurality of interlaced three mil copper signal and ground traces from a center signal trace and outer grounding ring respectively, with three mil spaces between traces interlaced in a way to gradually shunt the signal to ground over several milliseconds when contact between them is made by the conductive rubber button. A target pad is arranged on the center of the printed circuit board. An outer shell is surrounding the printed circuit board. A conductive rubber button is joined to a spring. A nylon outer sleeve is arranged against the conductive rubber button. A spring-loaded connector is arranged against the target pad and joined to a rubber sleeve.