Loudspeaker Voice Coil Temperature Control Using Evaluation Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating voice coil temperature in loudspeakers are either calibration-intensive, require sufficient signal energy, or fail during periods of low input signal, making them ineffective for continuous monitoring and timely temperature control, especially in small loudspeakers prone to overheating.
Innovation Solution
A sound system that generates an evaluation signal and combines it with the input sound signal to continuously monitor and control the voice coil temperature by adapting the loudspeaker signal based on monitored electric responses, allowing for accurate temperature management even during low-energy input signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prediction methods using mathematical models are used to estimate voice coil temperature, then temperature estimation can be performed, but calibration is required which increases device complexity and may require re-calibration over time
Solution Approach 1:
The system uses the loudspeaker's own operating signals to estimate voice coil temperature through electrical measurements, eliminating the need for external calibration equipment or procedures. The temperature estimation is performed self-service style using readily available electrical parameters from the voice coil during normal operation.
Solution Approach 2:
The patent replaces complex mathematical modeling and calibration procedures with direct electrical measurements. Instead of using sophisticated thermal models requiring parameter estimation, the system directly measures voltage and current to calculate instantaneous power and temperature, substituting mechanical/calibration-based approaches with electrical measurement-based approaches.
2Measurement precision
If current and voltage measurement methods are used to estimate voice coil temperature, then temperature can be determined from DC resistance, but sufficient signal energy is required which causes the method to fail during low input signal periods
Solution Approach 1:
The system continuously monitors electrical parameters and calculates temperature estimates in advance, maintaining readiness to provide temperature information even during low-signal periods. By continuously tracking power dissipation and maintaining temperature estimates based on accumulated electrical measurements, the system ensures temperature monitoring is always available without interruption.
Solution Approach 2:
The patent implements continuous temperature monitoring by constantly measuring voltage and current across the voice coil and calculating instantaneous power dissipation. This continuous measurement approach ensures that temperature estimation remains valid and updated at all times, including during periods of low input signal, eliminating gaps in monitoring coverage.
3Reliability
If power limiting methods are used to control voice coil temperature, then thermal damage can be prevented, but the input signal level must be continuously adjusted which affects sound quality
Solution Approach 1:
The system implements a feedback control mechanism where voice coil temperature is continuously monitored through electrical measurements, and this temperature information is fed back to control the input signal level. The feedback loop dynamically adjusts power delivery based on actual thermal conditions, preventing thermal damage while minimizing impact on sound quality by making adjustments only when necessary.
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 continuous and accurate voice coil temperature monitoring and control, reducing the risk of overheating and improving sound quality and loudspeaker lifespan by adapting the loudspeaker signal in real-time, regardless of input signal energy levels.
Implementation Method 1
From the measured voltage and current the DC resistance of the loudspeaker, also referred to as Re, is determined. The DC resistance is estimated as the average of the real part of the impedance for frequencies in the vicinity of the minimum impedance exceeding the resonant frequency of the loudspeaker. Since the DC resistance depends on the temperature of the voice coil, one may determine the temperature from the DC resistance.
Implementation Method 2
Loudspeakers are devices to convert electrical energy into acoustical energy.
Implementation Method 3
much of the electrical power that is applied to the loudspeaker results in heat dissipation
Data Source
AI summary
An audio controller for use with a loudspeaker that generates sound in dependence upon a loudspeaker signal is disclosed. The loudspeaker includes a voice coil. The audio controller includes a monitor to monitor an electric response of the voice coil to the loudspeaker signal and a signal generator to generate an evaluation signal. The evaluation signal comprises a signal having an evaluation frequency that is below resonant frequency of the loudspeaker. A processing unit is included to generate, based on the monitored electric response, the loudspeaker signal from an input sound signal. The processing unit is configured to combine the evaluation signal with the input sound signal to generate the loudspeaker signal.