Capacitive Trunk Access Sensor With Dual Detection Zones

The patent divides the detection space into multiple zones (first approach detection zone and second contact detection zone) using a single electrode combined with disjoint metal surfaces. Each metal surface creates a distinct capacitive field region, allowing the system to differentiate between approach and contact events without requiring multiple separate sensors, thus reducing device complexity while maintaining measurement precision through spatial segmentation of the capacitive field.

The patent introduces disjoint metal surfaces as intermediary elements between the single electrode and the user's limb. These metal surfaces act as capacitive couplings that extend and shape the electric field to create distinct detection zones, enabling the single electrode to effectively monitor multiple spatial regions without direct contact with each zone, thereby simplifying the sensor structure while preserving detection accuracy.

Instead of requiring the user to lift their foot toward the sensor (as in conventional foot-based systems), this patent inverts the interaction by placing the detection zones such that the user's limb naturally approaches or contacts the sensor during normal standing or walking motions. The disjoint metal surfaces create detection zones that are activated by passive limb proximity or contact rather than requiring active leg lifting, thereby maintaining hands-free operation while eliminating the fall hazard.

The system leverages the user's natural body movements and positioning during normal activity to trigger the detection zones. The disjoint metal surfaces and single electrode are positioned to detect limb approach or contact that occurs naturally during walking or standing, without requiring the user to perform additional actions like lifting the leg. The system serves itself by utilizing the user's inherent movements rather than demanding specific actions from the user.

The patent merges the functions of multiple electrodes into a single electrode system combined with disjoint metal surfaces. The single electrode generates an electric field that is shaped and extended by the disjoint metal surfaces to create multiple distinct detection zones. This merging approach achieves the same multi-zone detection reliability as multiple separate electrodes would provide, while significantly reducing device complexity and maintaining waterproof housing integrity without requiring multiple penetration points or complex sensor assemblies.

The single electrode combined with disjoint metal surfaces serves multiple functions simultaneously: it creates both the first approach detection zone and the second contact detection zone, provides waterproof sealing by requiring only a single electrode penetration point, and simplifies the overall sensor assembly. This multi-functional design achieves comprehensive detection zone coverage without increasing device complexity or compromising waterproof integrity.