Capacitive Vehicle Seat Sensor with Overlapping Strips
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Solution Overview
Problem
Capacitive seat sensor arrays face limitations in resolution and are prone to measurement errors due to limited sensing elements and parasitic coupling with metallic seat pans, increasing the cost of manufacture and installation.
Innovation Solution
A capacitive sensing apparatus featuring a deflectable dielectric mat with overlapping conductor strips on a flexible printed circuit, reducing parasitic coupling and increasing the number of capacitive load cells without raising costs, enhancing measurement resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensing elements is increased to improve measurement resolution, then measurement precision is improved, but electrical connection costs and device complexity increase
Solution Approach 1:
The patent transitions from planar sensor arrays to a three-dimensional configuration where conductor strips wrap around and overlap on both major surfaces of the dielectric mat. This spatial arrangement allows multiple sensing elements to be distributed throughout the seating volume rather than confined to a single plane, increasing measurement resolution without proportionally increasing electrical connection complexity
Solution Approach 2:
The sensor array is divided into multiple capacitive load cells formed by overlapping conductor strip regions. Each overlap region functions as an independent sensing element, allowing the system to achieve high measurement resolution through distributed sensing points while sharing common electrical infrastructure
2Ease of manufacture
If a lower metalized sensor film is used in capacitive sensing, then manufacturing cost is reduced, but parasitic coupling with metallic seat pan introduces measurement errors
Solution Approach 1:
A dielectric mat is introduced as an intermediary layer between the lower metalized conductor strips and the metallic seat pan. This dielectric barrier eliminates parasitic coupling between the sensor elements and the conductive seat pan, allowing the use of cost-effective metalized films without sacrificing measurement accuracy
Solution Approach 2:
The harmful parasitic coupling effect is extracted and isolated from the sensing system by placing the dielectric mat between the sensor elements and the seat pan, thereby removing the source of measurement errors while preserving the beneficial low-cost metalized film structure
3Measurement precision
If sensor pads with multiple sensing elements are installed to improve weight distribution detection, then measurement precision is improved, but device complexity and installation cost increase
Solution Approach 1:
Multiple sensing functions are merged into a single integrated structure where conductor strips wrap around and overlap on both surfaces of the dielectric mat. This unified design provides distributed weight distribution detection across the seat while simplifying installation compared to multiple separate sensor pads
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 improves measurement resolution and reduces errors by increasing the number of capacitive load cells while maintaining low manufacturing and installation costs, providing accurate occupant weight and distribution data.
Implementation Method 1
Overlapping regions of the conductor strips define an array of capacitive load cells distributed over the seating surface. A connector stub depending from the flexible printed circuit couples the conductor strips to an external circuit that measures the capacitance of the various load cells
Implementation Method 2
a capacitive sensing apparatus for a vehicle seat including a deflectable dielectric mat and a flexible printed circuit that wraps around the major surfaces of the dielectric mat
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A capacitive sensing apparatus (26) for a vehicle seat (10) includes a deflectable dielectric mat (28) and a flexible printed circuit (30) that wraps around the major surfaces of the dielectric mat (28) to define upper and lower conductor strips (34, 36) that overlap in a direction perpendicular to the dielectric mat (28). Overlapping regions of the conductor strips (34, 36) define an array of capacitive load cells distributed over the seating surface (14a). A connector stub (30d) depending from the flexible printed circuit (30) couples the conductor strips (34, 36) to an external circuit (40, 60) that measures the capacitance of the various load cells to determine occupant weight and weight distribution.