Earphone Volume Limiting Circuit for Sub-0.7 V Audio Signals
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Solution Overview
Problem
Existing sound volume limitation methods fail to effectively limit maximum sound volume in earphones or headsets when the signal source output voltage is less than 0.7 V, leading to potentially harmful high sound levels, and require specific adaptations or separate voltage sources, making them impractical for use with various signal sources and earplug types.
Innovation Solution
A sound volume limitation method that uses a voltage booster circuit to increase the signal voltage, allowing a detector device and shunt device to function at low voltages, and incorporates these components directly within the earphone or headset, ensuring compatibility with any signal source without affecting sound quality or requiring a separate battery source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prior art sound volume limitation methods are used with signal sources having output voltage less than 0.7 V, then the limitation function cannot operate, but the sound volume may become extremely high causing harm
Solution Approach 1:
The patent introduces a detector device as an intermediary component that senses the driving signal voltage and generates a control signal. This mediator enables the limitation function to operate by translating the low voltage driving signal into a usable control signal for the shunt device, resolving the contradiction between low input voltage and reliable limitation function.
Solution Approach 2:
The patent replaces the requirement for high voltage (mechanical/electrical constraint) with an electronic sensing and control system. Instead of relying on voltage level alone to activate limitation, the system uses electronic detection and signal processing to enable the shunt device to function at low voltages, substituting the voltage threshold requirement with an electronic control mechanism.
2Reliability
If software-based sound volume limitation is used in signal sources, then limitation can be achieved, but the earphone must be specifically adapted to that signal source and cannot be used with other sources
Solution Approach 1:
The patent makes the earphone universally compatible with different signal sources by integrating the limitation function directly into the earphone hardware. The detector device senses the driving signal regardless of its source, and the shunt device responds universally to the control signal, enabling the same earphone to work with any signal source while maintaining sound volume limitation capability.
Solution Approach 2:
The earphone performs the limitation function autonomously through its own detector and shunt devices, without requiring external software control from the signal source. The earphone self-regulates the sound volume based on its own sensing of the driving signal, making it independent of the signal source type and eliminating the need for source-specific adaptations.
3Reliability
If a separate battery-powered limitation device is used in the earphone, then sound volume can be limited, but the device becomes impractical and impossible for earplug types requiring frequent battery replacement
Solution Approach 1:
The earphone uses the existing driving signal from the signal source to power the detector device and generate the control signal for the shunt device. The system serves itself by extracting the necessary control information and power from the operational signal, eliminating the need for a separate battery and making the device practical for continuous use in earplug types.
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 limits sound volume across a wide range of signal sources, ensuring safety and practicality by maintaining sound quality and eliminating the need for specific adaptations or separate power sources, while ensuring compatibility with earplug types and various signal sources.
Implementation Method 1
a detector device for sensing the size of the output signal and for generating a control signal reflecting the size of the output signal
Implementation Method 2
a shunt device to which the control signal is connected and which is operative, on signals exceeding a given value, to shunt a part of the output signal past the earphone or headset
Data Source
AI summary
A method of limiting the maximum permitted sound volume in an earphone, a headset or the like, includes the step that the size of the driving signal for driving the earphone is sensed. The driving signal has a voltage that is less than approx. 0.7 V. If the driving signal exceeds a certain level, one part of the driving signal is shunted past the earphone and another part of the driving signal is diverted. Either the voltage of the diverted part is increased and controls the shunt device by which the first part of the driving signal is shunted past the earphone, or it is supplied to a unit with a detector device and the shunt device. The unit is sensitive to work at voltages below approx. 0.7 V. An earphone or the like for the above-mentioned method comprises a shunt device and a detector device whose current source is the signal source of the earphone.