Flexible PCB Safety Switch Mounting for Stable Cover Opening Detection
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Solution Overview
Problem
Existing opening detection systems in electronic devices suffer from false detections due to mechanical assembly inaccuracies and vibrations, which are not detectable during manufacturing and require costly adjustments to ensure reliable operation.
Innovation Solution
The implementation of a safety switch fixed to a flexible printed circuit board, directly connected to an electronic circuit via solder joints, simplifies the assembly by reducing the dimension chain and eliminating intermediate mechanical components, ensuring robust and reliable opening detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switch is mounted on a printed circuit board with multiple mechanical components (spacers, housing, cover), then the switch can be positioned close to the electronic circuit, but the large number of dimensions in the dimension chain leads to assembly inaccuracies and false detections
Solution Approach 1:
The patent extracts the switch from the complex mechanical assembly (housing, spacers, cover) and directly mounts it on the flexible printed circuit board. This removes the intermediate mechanical components that created the long dimension chain, eliminating the source of assembly inaccuracies while maintaining the switch's functional position.
Solution Approach 2:
The patent combines the switch mounting function directly with the flexible printed circuit board, eliminating the need for separate mechanical support structures. The switch is soldered directly to the FPCB, merging what were previously separate mechanical and electrical connection functions into a single integrated solution.
2Measurement precision
If the switch is positioned close to the electronic circuit, then the detection function is optimized, but the position of the moving part may be close to the reversed state, causing false triggers from shocks or vibrations
Solution Approach 1:
The patent uses a flexible printed circuit board that can dynamically adapt to slight position variations while maintaining stable electrical connection. The flexibility allows the system to absorb mechanical shocks and vibrations without causing false switch state changes, while still maintaining precise positioning for accurate detection.
3Reliability
If adjustment of part positions is performed to compensate for mechanical assembly variations, then detection reliability improves, but manufacturing cost increases and reproducibility decreases
Solution Approach 1:
The flexible printed circuit board serves itself by providing both mechanical support and electrical connection for the switch. The FPCB's inherent flexibility compensates for assembly variations without requiring external adjustment mechanisms, making the system self-regulating and eliminating costly adjustment steps while maintaining high reliability.
Data Source
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Figure 3~4
AI summary
The invention relates to electronic equipment (10) comprising a housing (16), a cover (18) closing the housing (16), an electronic circuit (12) disposed within the housing (16), and a safety switch (20) configured to detect an opening of the cover (18). The safety switch (20) is fixed to a flexible printed circuit board (22) connecting the safety switch (20) to the electronic circuit (12). The flexible printed circuit board (22) is fixed to the housing (16) opposite the safety switch (20). The invention also relates to a method for manufacturing the electronic equipment (10).