Panel Speaker Back Cover Damping Layer for Audio Leakage
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Solution Overview
Problem
Conventional mobile devices with panel speakers suffer from audio signal leakage through the back cover, compromising user privacy due to the acoustic coupling of polycarbonate back covers with internal components, which affects the acoustic performance and privacy.
Innovation Solution
Incorporating a movable section actuated by a piezoelectric actuator and a damping layer, such as an epoxy material, between the chassis and the back cover to attenuate vibrations and limit sound transmission through the back cover, thereby reducing privacy leakage and maintaining acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polycarbonate back cover is acoustically coupled to internal portions of the phone, then structural integrity and assembly ease are improved, but audio signal leakage through the back cover increases, compromising user privacy
Solution Approach 1:
A damping layer is introduced as an intermediary material between the back cover and the chassis. This damping layer acts as a mediator that blocks the acoustic coupling path, preventing audio signals from leaking through the back cover while maintaining the structural integrity of the overall assembly.
Solution Approach 2:
The back cover assembly becomes a composite structure consisting of multiple layers: the polycarbonate back cover, the damping layer in between, and the chassis. This composite material approach allows the system to simultaneously achieve structural strength from the rigid components and acoustic isolation from the damping material.
2Manufacturing precision
If the back cover is rigidly coupled to the chassis, then manufacturing precision and assembly ease are improved, but vibration transmission and sound leakage increase
Solution Approach 1:
The damping layer serves as an intermediary that decouples the rigid connection between the back cover and chassis. While the overall assembly remains precise, the damping layer interrupts the direct vibration transmission path, reducing sound leakage without compromising assembly precision.
3Device complexity
If no damping layer is used, then device complexity is reduced, but audio signal leakage and privacy compromise increase
Solution Approach 1:
The damping layer is a relatively simple, thin material layer that can be easily integrated into the back cover assembly. While it adds a component, the damping layer is simple in construction and can be applied as a thin film or coating, minimizing the increase in overall device complexity while effectively addressing acoustic leakage.
4Reliability
If the back cover is made from acoustically transparent material, then acoustic performance is improved, but privacy leakage through the back cover increases
Solution Approach 1:
The damping layer is strategically placed only in specific locations where acoustic leakage is problematic, such as between the back cover and chassis. This localized application maintains acoustic performance in other areas while preventing privacy leakage through the back cover, achieving different acoustic properties in different parts of the structure.
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 reduces sound pressure levels and privacy leakage by absorbing and weakening sound waves, ensuring that audio signals are primarily directed to the user while minimizing emissions through the back cover, thus enhancing user privacy and acoustic output.
Implementation Method 1
a damping layer, such as an epoxy material, between the chassis and the back cover to attenuate vibrations
Implementation Method 2
absorbing and weakening sound waves
Implementation Method 3
at least one actuator configured to actuate the movable section, the actuator being in communication with electronic circuitry and configured to generate an acoustic signal substantially from the movable section when the at least one actuator is driven by an audio signal
Data Source
AI summary
An apparatus comprises a movable section for sound generation; at least one actuator configured to actuate the movable section, the actuator being in communication with electronic circuitry and configured to generate an acoustic signal substantially from the movable section when the at least one actuator is driven by an audio signal; and a back cover coupled to the movable section and configured to limit the generation of sound from the back cover by attenuating vibrations that are caused when the movable section is actuated by the at least one actuator. The movable section and the at least one actuator define a panel speaker.