Vehicle Door Handle Capacitive Press Detection Under Sealed Covers
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Solution Overview
Problem
Capacitive proximity sensors in vehicles are sensitive to environmental influences such as snow, rain, and air humidity, leading to erroneous detections, and are affected by metal coatings, while mechanical contact switches are expensive and disrupt the vehicle's appearance.
Innovation Solution
A door handle arrangement with a mechanically stable, electrically insulating cover that has an actuating surface on which pressure is applied, featuring an actuating electrode on the inner side and a sensor electrode inside, allowing for capacitive detection without environmental interference, enabling any exterior configuration including metal coatings without sensitivity loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If capacitive proximity sensors are used to detect user approach, then keyless entry functionality is enabled, but environmental influences such as snow, rain, and humidity cause erroneous detections
Solution Approach 1:
The patent introduces an electrically insulating cover as an intermediary element between the capacitive sensor and the external environment. This cover allows the sensor to detect user approach while protecting it from environmental influences like snow, rain, and humidity that would otherwise cause erroneous detections.
Solution Approach 2:
The patent employs a thin, electrically insulating cover that acts as a flexible barrier. This cover is sufficiently thin to allow capacitive field penetration for detection purposes while being thick enough to provide environmental protection, effectively solving the contradiction between accessibility and protection.
2Shape
If metal coatings are applied to the door handle exterior, then aesthetic appearance and durability are improved, but capacitive sensing in the outer area is inhibited
Solution Approach 1:
The patent segments the door handle into distinct functional zones: an outer aesthetic area that can be metal-coated for appearance and durability, and an inner sensing area where the capacitive sensor is protected from metal coatings. This segmentation allows both metal coating benefits and capacitive sensing to coexist without interference.
Solution Approach 2:
The electrically insulating cover serves as a mediator that separates the metal-coated exterior from the capacitive sensor. It allows the exterior to have metal coatings for aesthetic purposes while preventing these coatings from interfering with the capacitive sensing function.
3Reliability
If mechanical contact switches are used for pressure detection, then reliable actuation detection is achieved, but appearance is disrupted and sealing costs increase
Solution Approach 1:
The patent replaces mechanical contact switches with a capacitive sensing system. This substitution eliminates the need for mechanical moving parts and complex sealing mechanisms, while maintaining reliable actuation detection through changes in capacitance when pressure is applied to the actuating surface.
Solution Approach 2:
The patent uses a thin, electrically insulating cover that can be sealed with simple edge sealing techniques. This flexible cover approach is much simpler than sealing mechanical switches, reducing device complexity and sealing costs while maintaining reliable pressure detection through capacitive changes.
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 reliable and sensitive pressure actuation detection, immune to environmental influences and allowing flexible exterior configurations, while maintaining a sealed and aesthetically appealing design.
Implementation Method 1
A control and evaluation circuit is coupled at least to the sensor electrode to detect a capacitance between the sensor electrode and the actuating electrode
Implementation Method 2
The cover is elastically deformable by an actuation in the area of the actuating surface
Data Source
AI summary
A door handle arrangement for vehicles including an electrically insulating cover having an outer actuating surface for a user characterized by at least one metal actuating electrode disposed on the inner side of the cover that is on the side of the cover facing away from the actuating surface. The cover is elastically deformable by an actuation in the area of the actuating surface. The arrangement includes at least one sensor electrode that is disposed at a distance from the actuating element and opposite the inner side of the cover, wherein the sensor electrode lies opposite the actuating electrode at least in certain sections so that the distance between actuating electrode and sensor electrode is variable during deformation of the cover in the region of the actuating surface. The arrangement also includes a control and evaluation device which is coupled at least to the sensor electrode to detect a capacitance between sensor electrode and actuating electrode.