Membrane Switch Segmentation for Seat Occupancy Detection
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Solution Overview
Problem
Existing seat occupancy detection systems fail to accurately differentiate between occupants and luggage due to variations in seating posture and thermal conditions, leading to incorrect detection of seating states, especially when occupants are positioned deviated from the standard seating position or in low-temperature environments.
Innovation Solution
A seat occupancy detection device featuring a membrane switch with contact portions arranged in a straight line, positioned to ensure that at least two contact portions are activated simultaneously by the seating load, strategically placed across multiple seating load areas to prevent false detection, including areas most deviated in the longitudinal or lateral direction, and positioned outside non-detecting areas to account for temperature-induced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thin and flexible membrane switch with sensor cells is used to detect seating state, then the seating state can be detected, but false detection occurs when luggage is placed on the seat or when occupants are positioned deviated from standard position
Solution Approach 1:
The membrane switch is divided into multiple independent contact portions (first contact portion, second contact portion, third contact portion) arranged in a specific pattern. Each contact portion can be independently activated, and the system requires a specific combination (at least two adjacent contact portions) to trigger occupancy detection, thereby distinguishing between luggage and actual occupants.
Solution Approach 2:
The contact portions are pre-positioned and pre-configured in specific patterns on the membrane switch before installation. The arrangement of contact portions is designed in advance to cover multiple possible seating positions and postures, ensuring that regardless of where the occupant sits or how they position themselves, at least two adjacent contact portions will be activated.
2Strength
If the seat cushion material is hardened at low temperature to maintain structural integrity, then the structural integrity is improved, but the area to which pressure is applied decreases leading to detection failure
Solution Approach 1:
The membrane switch with contact portions is strategically positioned at specific locations on the seat cushion where pressure is most likely to be applied regardless of temperature-induced material hardening. The contact portions are arranged to detect pressure in areas that maintain contact even when the cushion material becomes harder at low temperatures.
Solution Approach 2:
The contact portions are pre-positioned to anticipate and account for temperature effects on the seat cushion material. The arrangement ensures coverage of pressure application areas under various thermal conditions, so that even when the material hardens, the contact portions remain in positions where pressure will be applied.
3Adaptability or versatility
If the occupant position is deviated from the standard position in longitudinal or lateral direction, then seating comfort is improved, but the seating load area moves away from the sensor cells leading to detection failure
Solution Approach 1:
Multiple contact portions are distributed across different areas of the membrane switch to cover a wide range of possible seating positions. The segmented arrangement ensures that regardless of lateral or longitudinal deviation from the standard position, at least two adjacent contact portions will be activated by the occupant's weight.
Solution Approach 2:
The membrane switch with its pattern of contact portions serves multiple detection functions simultaneously - it can detect occupancy at standard position, deviated positions, various postures, and different temperatures, making it a universal detection solution for all seating scenarios.
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 reliably detects the seating state of occupants by preventing false activation from luggage or positional deviations, ensuring accurate operation of safety apparatuses like airbags and seatbelts, while maintaining detection accuracy across various temperatures and seating positions.
Implementation Method 1
a membrane switch which is formed in a bar shape and is provided at a seat cushion... outputs a seat occupancy detection signal when two contact portions from among the plurality of contact portions are turned on at the same time by a load of an occupant
Data Source
Figure 1~3
Figure 4~7
Figure 8~9
AI summary
A seat occupancy detection device (2, 52) includes a membrane switch (4, 54.) formed in a bar shape which includes plural contact portions (6) arranged in a straight line and outputs a seat occupancy detection signal when two contact portions (6) from among the plural contact portions (6) are turned on at the same time by a load of an occupant seated on a seat cushion (1), the two contact portions (6) being arranged at at least every other contact portion (6). The membrane switch (4, 54) is provided at the seat cushion (1) so that at least the two contact portions (6) are positioned in a seating load area that receives the load of the occupant when the seating load area is most deviated in a longitudinal or a lateral direction relative to a standard position.