Capacitive Proximity Sensor Driven Shield for Hands-Free Liftgate
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Solution Overview
Problem
Existing hands-free vehicle entry systems face challenges such as user difficulty in executing kick responses, misinterpretation of user actions, and malfunction due to environmental contaminants, particularly for users with loaded arms or in noisy conditions, and the need for special dexterity to interact with sensors.
Innovation Solution
A hands-free closure control device integrated with a capacitive proximity sensor and driven shield, mounted on a vehicle's license plate area, which detects authorized users' presence and proximity without requiring special dexterity, using a capacitive proximity sensor system that shields the sensor from the vehicle's ground plane to enhance directional detection and reduce ambient interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a kick response detector is used for hands-free liftgate operation, then the user can open the liftgate without manual intervention, but users with loaded arms have difficulty executing the kick motion and the system may misinterpret user actions
Solution Approach 1:
The patent replaces the mechanical kick detection system with a capacitive proximity sensing system. Instead of detecting physical kick motions that require user dexterity, the capacitive sensor detects the presence and proximity of authorized users through electrical field changes, eliminating the need for complex physical gestures while improving detection reliability.
Solution Approach 2:
The patent introduces a capacitive sensor as an intermediary between the user and the liftgate opening mechanism. This intermediary detects user presence through electrical field interactions rather than requiring direct physical contact or specific motions, providing a more reliable and accessible interface for all users.
2Ease of operation
If a proximity sensor is mounted under the vehicle for kick detection, then hands-free operation is enabled, but the sensor malfunctions when covered by road and weather contaminants
Solution Approach 1:
The patent relocates the capacitive proximity sensor from the underside of the vehicle to the license plate area on the rear exterior surface. This dimensional relocation moves the sensor from a contaminated environment (under the car where mud and snow accumulate) to a more accessible and cleaner location that remains exposed but is easier to maintain.
Solution Approach 2:
The patent uses the license plate mounting area as a copy of a standard vehicle feature that is already positioned in an optimal location for proximity sensing. By integrating the sensor into this existing structure, the system benefits from the license plate area's natural positioning and accessibility without requiring separate mounting structures.
3Ease of operation
If a capacitive proximity sensor is integrated into the license plate area, then user accessibility is improved and special dexterity is not required, but the sensor may be affected by the vehicle's ground plane
Solution Approach 1:
The patent introduces a driven shield as an intermediary element between the capacitive sensor and the vehicle's ground plane. This driven shield, positioned behind the sensor, electrically isolates the sensor from the ground plane's interfering electrical fields while allowing the sensor to detect user presence, thereby eliminating the harmful interference.
Solution Approach 2:
The patent converts the potentially harmful ground plane interference into a beneficial reference potential. By using the driven shield technique, the ground plane's electrical field is transformed from a source of noise into a stable reference that enhances the sensor's ability to detect changes in capacitance caused by user proximity.
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
Enables reliable and convenient hands-free operation of vehicle closures like liftgates, maintaining system reliability and user accessibility without the need for special dexterity, while minimizing false triggers and environmental interference.
Implementation Method 1
A capacitive proximity sensor, with a front and back, each capable of generating an electric field
Implementation Method 2
A driven shield is arranged to shield the back side of the capacitive proximity sensor from the effects of any proximate ground plane established by the vehicle body and to shift the electric field to the front side of the capacitive proximity sensor
Data Source
AI summary
A hands-free opener for a power liftgate provides a proximity sensor that fits into an operating position behind the vehicle license plate or in the license plate area. A driven shield located behind the sensor shapes the electric field from the sensor to achieve directional detection extending outward from the front side of the sensor. A proximate ground plane at a preselected spacing from the back side of the ground plane reduces interference.