Seat Occupancy Sensor Using Logical AND Gate
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Solution Overview
Problem
Current seat occupancy sensors for motor vehicles are costly and complex, particularly for applications not critical to safety, as they require a matrix circuit and a sophisticated evaluating processor unit for precise classification of seat occupancy.
Innovation Solution
A simplified seat occupancy sensor using at least two switch elements connected as a logical AND gate, arranged with a certain distance between them, allowing detection of seat occupancy only when both elements are actuated, thereby distinguishing between local and wide-area occupancy without the need for a costly matrix circuit or processor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a matrix circuit with multiple switch elements and an evaluating processor unit is used, then measurement precision of seat occupancy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential function of occupancy detection from the complex matrix circuit and processor system, retaining only the critical switch elements needed for basic occupancy detection. By removing the evaluating processor unit and complex matrix circuitry, the invention achieves adequate occupancy detection for non-safety applications while dramatically reducing system complexity and cost.
Solution Approach 2:
The patent employs simple, inexpensive switch elements that can be easily manufactured and replaced, replacing the need for expensive processor units and complex circuit boards. This approach uses low-cost components to achieve the necessary functionality for seat belt warning systems, where high precision is not critical.
2Measurement precision
If a matrix circuit with multiple switch elements is used, then measurement precision of seat occupancy is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses inexpensive switch elements and simple circuitry that can be manufactured at low cost, eliminating the need for expensive processor units and complex matrix circuits. This approach significantly reduces manufacturing costs while providing sufficient occupancy detection capability for non-safety applications.
Solution Approach 2:
The invention removes the costly evaluating processor unit and complex matrix circuitry from the system, retaining only the essential switch elements needed for basic occupancy detection. This extraction of essential functions dramatically reduces manufacturing costs while maintaining adequate performance for seat belt warning systems.
3Reliability
If switch elements are arranged with distance between them, then false activation from local objects is prevented, but detection capability for accurate occupancy classification is reduced
Solution Approach 1:
The patent positions switch elements at specific asymmetric locations on the seat surface, spaced far enough apart to prevent false activation by small objects like handbags, yet positioned to detect the distributed pressure pattern of a human body. This asymmetric arrangement optimizes the balance between false activation prevention and occupancy detection capability for non-safety applications.
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 solution enables a cost-effective and straightforward detection of seat occupancy, capable of distinguishing between local and wide-area occupancy, effectively preventing false activations in non-safety critical applications like seat belt warnings, while maintaining sufficient accuracy for passenger detection.
Implementation Method 1
at least two switch elements (12, 14) actuatable by pressure
Data Source
AI summary
The invention relates to a seat occupancy sensor (10) comprising at least two switch elements (12, 14) which can be activated by pressure. Said elements can be associated with the surface of a seat and are arranged at a certain distance from each other in such a manner that a first switch element (12) is associated with a first area of the seat and a second switch element (14) is associated with a second area of the seat. According to the invention, the first and second switch elements (12, 14) are connected to each other in such a manner that a logical AND-linkage is produced. The first and second switch elements are, for example, serially connected in a particularly simple embodiment of the invention.