Vehicle Seat Load Sensor FPC Wiring Segmentation
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Solution Overview
Problem
Existing occupant load sensors for vehicles face issues with deformation of wiring patterns on the sensor substrate due to strain, affecting sensor output and requiring a large space to avoid contact between strain detecting elements and wiring patterns.
Innovation Solution
The design includes a strain member with strain gauge plates forming half-bridge circuits, an amplifier substrate, and an FPC substrate with wiring patterns that form the Wheatstone bridge circuit, allowing for precise load measurement without significant deformation of wiring patterns and minimizing space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wiring patterns are formed on the sensor substrate, then electrical connections are established, but the wiring patterns deform when the sensor substrate is strained, affecting sensor output
Solution Approach 1:
The patent divides the electrical connection system into two separate parts: strain detecting elements formed on the sensor substrate and wiring patterns formed on a separate flexible printed circuit board. This segmentation prevents the wiring patterns from deforming with the sensor substrate, eliminating the source of measurement error while maintaining electrical connectivity through the FPC substrate connection.
2Measurement precision
If strain detecting elements and wiring patterns are arranged to avoid contact, then measurement accuracy is improved, but a larger space is required
Solution Approach 1:
The patent moves the wiring patterns from the two-dimensional plane of the sensor substrate to a separate flexible printed circuit board that connects to the sensor substrate. This dimensional transition allows the strain detecting elements and wiring patterns to coexist without spatial conflict, achieving both measurement precision and compactness by utilizing the third dimension for circuit routing.
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
This configuration enables precise measurement of occupant load while preventing deformation of wiring patterns and avoiding contact between strain detecting elements, resulting in a compact and reliable occupant load sensor.
Implementation Method 1
a strain is generated to the sensor substrate. The strain is detected as a resistance change of each strain detecting element
Implementation Method 2
first and fourth strain detecting elements are connected by circuit patterns, so that a Wheatstone bridge is structured. The resistance change is transformed to electric voltage in the Wheatstone bridge
Data Source
AI summary
An occupant load sensor of a seat for a vehicle includes a strain member, a connecting member, first and second strain gauge plates, an upper bracket, an amplifier substrate, and an FPC substrate. The strain gauge plates are attached to a surface of the strain member and respectively arranged between a central portion and both end portions of the strain member. Each strain gauge plate includes two strain detecting elements forming a half bridge circuit of a Wheatstone bridge circuit. The FPC substrate is connected to the amplifier substrate and to the strain gauge plates between the both end portions and the central portion of the strain member. Further, the FPC substrate includes a plurality of wiring patterns. The Wheatstone bridge circuit is formed with the plurality of wiring patterns and the half bridge circuit formed at each strain gauge plates.