Panel Loudspeaker Temperature Control Using Coil Energy Modeling

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Solution Overview

Problem

Panel audio loudspeakers face challenges in monitoring and controlling temperature to prevent user injury and damage due to high temperatures caused by actuator operation, particularly in devices like mobile phones and smart watches.

Innovation Solution

A system is implemented that includes an actuator with a magnetic coil in thermal communication with the panel, electrical sensors, and an electronic control module to monitor temperature by measuring electrical data, using a thermal model to adjust the audio signal supplied to the coil based on energy and temperature changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the magnetic coil operates at high power to produce sufficient sound output, then the audio performance is improved, but the panel temperature increases causing potential user injury and component damage

Engineering Contradiction:
Improveaudio output powerVSAvoidpanel temperature
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The system performs preliminary thermal modeling and prediction before the panel temperature actually reaches dangerous levels. The control module continuously predicts future temperature based on current power consumption and thermal characteristics, allowing preventive action to be taken before overheating occurs

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements a closed-loop feedback mechanism where the control module continuously monitors power consumption, predicts temperature using thermal models, and adjusts the audio signal accordingly. This feedback loop enables dynamic temperature control that maintains safe operating conditions while preserving audio performance

Inventive Principle:
Principle #23Feedback

2Temperature

If the current to the magnetic coil is reduced to lower temperature, then panel temperature is controlled, but the audio output quality deteriorates

Engineering Contradiction:
Improvepanel temperatureVSAvoidaudio output power
Core Design Contradiction:
TemperatureVSPower

Solution Approach 1:

The system dynamically adjusts the audio signal parameters based on real-time temperature predictions and thermal models. Rather than using a fixed reduction, the control module continuously adapts the signal characteristics (amplitude, frequency, duration) to maintain optimal balance between temperature control and audio quality

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes multiple audio signal parameters simultaneously (amplitude, frequency, duty cycle) rather than simply reducing current. This multi-parameter adjustment allows the system to maintain perceived audio quality while controlling thermal output through sophisticated signal processing

Inventive Principle:
Principle #35Parameter changes

3Reliability

If thermal modeling and temperature prediction systems are implemented, then temperature control capability is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature control reliabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system uses the existing magnetic coil's electrical characteristics (impedance, current draw) to infer temperature information without requiring separate temperature sensors. The thermal model leverages readily available electrical data from the audio signal path, allowing the system to self-monitor and self-regulate temperature

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system replaces physical temperature sensors and complex thermal management hardware with computational thermal modeling. By using mathematical models that process electrical signal data, the system achieves accurate temperature prediction without additional mechanical or electronic sensing components

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Effectively regulates panel temperature to maintain it below harmful levels, preventing damage and injury by adjusting the audio signal to control heat generation and dissipation.

Implementation Method 1

an actuator including a magnetic coil that provides a force to a panel, causing the panel to vibrate to produce audible sound waves

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The magnetic coil of the actuator may be in thermal communication with the panel, such that heat can flow between the magnetic coil and the panel

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4101180B1Panel loudspeaker temperature monitoring and control
Publication Date: 2025.07.02 GOOGLE LLC
  • EP4101180B1 patent drawingFigure 1~2
  • EP4101180B1 patent drawingFigure 3
  • EP4101180B1 patent drawingFigure 4

AI summary

A panel audio loudspeaker includes a panel and an actuator attached to a surface of the panel and configured to cause vibration of the panel. The actuator comprises a magnetic coil in thermal communication with the panel. The panel audio loudspeaker further comprises a plurality of electrical sensors electrically coupled to the magnetic coil and configured to output time-varying electrical data for the magnetic coil, and an electronic control module in communication with the magnetic coil and the electrical sensors. The electronic control module is configured to perform operations comprising: providing a current to the magnetic coil; receiving the time-varying electrical data for the magnetic coil; determining an electrical energy provided to the magnetic coil between a first time and a second time; accessing a thermal model of the panel; and determining a change in a panel temperature between the first time and the second time.