Sound Device FPC Welding Layout for Magnetic Field Performance
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Solution Overview
Problem
Existing sound devices in portable mobile terminals suffer from reduced magnetic field performance due to thinning of the pole plate and glue overflow affecting vibration ability, which compromises sound quality.
Innovation Solution
A sound device design featuring a magnet system with interconnected magnetic gaps and a vibration system with FPCs arranged to avoid thinning the inner yoke and prevent glue overflow, ensuring the thickness of the yoke and improving magnetic and vibration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an avoidance groove is provided on the pole plate to avoid the solder pad, then the solder pad can be positioned for welding convenience, but the pole plate thickness is reduced resulting in loss of magnetic field BL
Solution Approach 1:
The patent moves the solder pad from the pole plate to the FPC board, changing the spatial dimension of the welding location. This allows the solder pad to be positioned on the FPC surface rather than requiring an avoidance groove in the pole plate, thus maintaining pole plate thickness while achieving welding accessibility.
Solution Approach 2:
The FPC board serves as an intermediary carrier for the solder pad, separating the welding function from the magnetic field structure. The solder pad is now located on the FPC rather than the pole plate, eliminating the conflict between welding access and magnetic field integrity.
2Strength
If the glue is used to bond the FPC and the coil, then the components can be fixed together, but the glue overflows to sides of the coil negatively affecting the vibration ability of the vibration system
Solution Approach 1:
The patent introduces a groove structure on the FPC surface that creates a localized bonding region. The glue is confined to this specific groove area, ensuring strong bonding between FPC and coil while preventing glue from spreading to the coil sides and interfering with vibration motion.
Solution Approach 2:
The groove structure acts as a confining structure that guides and limits the glue application. By creating a defined bonding channel, the glue remains contained within the groove boundaries, preventing harmful overflow while maintaining adequate bonding strength.
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
Enhances magnetic field performance and vibration ability, thereby improving sound quality by maintaining yoke thickness and preventing glue overflow.
Implementation Method 1
a coil configured to drive the diaphragm
Implementation Method 2
a magnet system having a first magnetic gap and a second magnetic gap interconnected with each other
Data Source
AI summary
The present disclosure discloses a sound device including a frame, a magnet system, and a first vibration system and a second vibration system. The magnet system includes a first inner yoke, a main magnet fixed to the first inner yoke, and a second inner yoke fixed to one side of the main magnet away from the first inner yoke; the first vibration system includes a first diaphragm, a first coil surrounding the second inner yoke, and a first FPC electrically connected with the first coil; the first coil includes a first corner portion; the first FPC includes a first fixation portion, a first welding portion welded to the first coil, and a first elastic portion; the first welding portion is located on one side of the first corner portion away from the second inner yoke. The sound device has better magnetic field performance and vibration performance.