Loudspeaker Dual Functionality via Frequency Domain Isolation
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Solution Overview
Problem
Conventional loudspeakers can only perform either sound reproduction or detection at a given time, limiting their dual functionality in applications requiring simultaneous sound generation and sensing.
Innovation Solution
A circuit with isolation filters, including a low-pass and high-pass filter combination, allows a loudspeaker to generate an acoustic signal while simultaneously sensing a second acoustic signal by suppressing overlapping frequency components, enabling concurrent sound reproduction and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a loudspeaker is used for sound reproduction, then acoustic signal generation is achieved, but simultaneous sound detection is not possible
Solution Approach 1:
The patent segments the frequency spectrum into distinct bands: the input signal occupies higher frequencies while the sensed signal occupies lower frequencies. By filtering out the higher frequency components from the loudspeaker terminal output, the system can simultaneously extract the lower frequency sensed signal without interference from the reproduction signal, enabling true simultaneous dual functionality.
Solution Approach 2:
The patent applies frequency-selective filtering to different parts of the signal spectrum. The isolation means specifically targets and removes frequency components corresponding to the input signal while preserving frequency components corresponding to the sensed signal. This local frequency-domain processing enables simultaneous sound reproduction and detection without time multiplexing.
2Device complexity
If a loudspeaker is used as both input and output device, then device complexity is reduced, but signal separation becomes difficult
Solution Approach 1:
The patent changes the frequency parameter of the sensed signal to occupy a different band (lower frequencies) from the reproduction signal (higher frequencies). The isolation means then exploits this frequency parameter difference to separate the two signals, making signal separation straightforward through frequency-domain filtering rather than requiring complex spatial or temporal separation techniques.
3Device complexity
If the same loudspeaker is used alternately for reproduction and detection, then component count is reduced, but functional versatility is limited
Solution Approach 1:
The patent makes the loudspeaker truly multi-functional by enabling it to simultaneously perform both sound reproduction and sound detection. The isolation means allows the loudspeaker terminal to serve dual purposes: driving the loudspeaker for reproduction while also sensing external sounds. This concurrent operation capability represents full universality, allowing the system to function as both output and input device at the same time rather than alternating between modes.
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
Enables the loudspeaker to function as both a sound generator and sensor, allowing for applications like pedometer integration and user control through footstep or tapping detection without a separate microphone, enhancing usability and functionality.
Implementation Method 1
a loudspeaker and a microphone are transducers capable of converting between electrical energy and acoustic energy. In a loudspeaker, the conversion is intended to be from an electrical driving signal input to the loudspeaker into output acoustic energy
Implementation Method 2
In a microphone the reverse is intended - incident acoustic waves cause movement of part of the microphone, which induces an electrical signal
Implementation Method 3
isolation means comprising a first filter which is adapted to suppress a signal component related to the first electrical signal while simultaneously passing the second electrical signal to the output
Data Source
Figure 1~2
Figure 3~4
AI summary
Apparatus for generating a first acoustic signal and simultaneously sensing a second acoustic signal. The apparatus comprises: an input (15) for receiving a first electrical signal from a signal source; a loudspeaker terminal, directly or indirectly connected to the input (15), for connection to a loudspeaker (30) for generating the first acoustic signal in response to the first electrical signal and for generating a second electrical signal in response to the second acoustic signal; and an output (35), for outputting the second electrical signal. The loudspeaker terminal is connected to the output (35) via isolation means (25) comprising a first filter which is adapted to suppress a signal component related to the first electrical signal while simultaneously passing the second electrical signal to the output (35).