Capacitive Sensor Force Translation Plates
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Solution Overview
Problem
Existing occupant presence detection systems in vehicles, such as those using fluid-filled bladders or capacitive sensors, face challenges in accurately and cost-effectively determining passenger weight and classification, particularly in varying environmental conditions.
Innovation Solution
A capacitive sensor apparatus comprising rigid force translation plates and conductor plates separated by a dielectric substance, biased by springs, which measures the gap capacitance between the plates to detect passenger weight and classify occupants as child, adult, or other, with a control circuit to interpret the capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluid-filled bladder with pressure sensor is used for occupant presence detection, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical pressure sensor system with an electrical capacitive sensing system. Instead of using a fluid-filled bladder with a pressure sensor, the invention uses two conductor plates that form a capacitor, where the capacitance changes in response to occupant presence. This substitution of mechanical sensing with electrical sensing simplifies the device structure while maintaining detection reliability.
Solution Approach 2:
The patent extracts and eliminates the fluid-filled bladder component from the sensor system. By removing the complex fluid containment structure and pressure sensing mechanism, the invention achieves a simpler design that uses only conductor plates and electronic circuitry to detect occupant presence, thereby reducing device complexity while preserving detection functionality.
2Ease of manufacture
If conductor plates are placed on fluid-filled bladder surfaces for capacitive sensing, then cost is reduced by eliminating pressure sensor, but measurement precision deteriorates due to fluid compliance
Solution Approach 1:
The patent replaces the fluid-filled bladder mechanical system with a rigid structural support system. Instead of relying on fluid compliance to transmit force, the invention uses rigid plates that directly translate applied force into capacitance changes, eliminating the compliance-induced measurement errors while maintaining the cost benefits of capacitive sensing.
Solution Approach 2:
The patent introduces rigid force translation plates as intermediaries between the occupant load and the conductor plates. These rigid plates serve as mediators that directly transmit force without the compliance and variability associated with fluid-filled bladders, thereby improving measurement precision while maintaining the simplified capacitive sensing approach.
3Device complexity
If foam or compressible material is used instead of fluid-filled bladder in capacitive sensor, then device complexity is reduced, but measurement precision and reliability worsen due to material variability
Solution Approach 1:
The patent replaces the compressible foam mechanical system with a rigid plate structure. Instead of using foam material that compresses and varies in properties, the invention uses rigid force translation plates that maintain consistent mechanical properties and directly translate force into measurable capacitance changes, thereby improving measurement precision while keeping the device structure simple.
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 provides a practical and cost-effective means for passenger presence detection and classification, offering improved accuracy and reliability by effectively measuring weight changes and compensating for environmental variations, such as humidity and electromagnetic interference.
Implementation Method 1
first and second mutually parallel rigid force translation plates biased apart by a set of springs
Implementation Method 2
a capacitor having first and second mutually parallel plates separated by a dielectric substance disposed therebetween
Data Source
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AI summary
A capacitive sensor apparatus (12) is disposed between the bottom cushion (18) and frame (16) of a seat (10). The sensor apparatus (12) includes first and second mutually parallel rigid force translation plates (22, 24) biased apart by a set of springs (26), first and second conductor plates (28, 30) centrally affixed to inboard faces of the first and second force translation plates (22, 24), and a control circuit (32) responsive to the gap capacitance between the first and second conductor plates (28, 30). The force translation plates (22, 24) are joined in a manner to maintain the conductor plates (28, 30) parallel to each other while permitting movement of either force translation plate relative to the other in a mutually perpendicular direction.