Capacitive Indirect Contact Sensing Using a Grounding Conductor
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Solution Overview
Problem
Capacitive touch sensing systems cannot detect indirect contact between conductors, as they only sense direct contact with the sensing electrode and fail to register subsequent contacts.
Innovation Solution
A capacitance-type sensing system that includes a capacitance-type sensor with a grounding conductor, where the grounding conductor has a large contact area, forming an effective loop with the sensing electrode and driving circuit to detect changes in capacitance values when conductors make contact, allowing for the determination of indirect contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional capacitance sensor is used to detect direct contact with the sensing electrode, then direct contact detection is achieved, but indirect contact between conductors cannot be detected
Solution Approach 1:
The patent introduces a grounding conductor as an intermediary element that mediates between the sensing electrode and the indirect contact target. This grounding conductor serves as a reference potential that enables the detection of indirect contacts by providing a complete electrical path for capacitance measurement, thus resolving the limitation of conventional sensors that can only detect direct contacts.
Solution Approach 2:
The patent extends the sensing capability from a single-point direct contact detection to a distributed field-based indirect contact detection. By introducing the grounding conductor with a larger contact area, the system transitions from detecting only direct electrode contact to detecting capacitance changes through an extended grounding reference, adding a spatial dimension to the sensing capability.
2Measurement precision
If the grounding conductor contact area is increased to improve indirect contact detection, then sensing accuracy is improved, but device size and complexity increase
Solution Approach 1:
The patent applies local quality by concentrating the large contact area requirement specifically on the grounding conductor portion that interfaces with the grounding surface, while keeping the sensing electrode and other critical components compact. This localized expansion of contact area achieves improved sensing accuracy without requiring the entire device to be large-scale.
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 accurate and effective sensing of indirect contact by forming a larger signal loop, improving the ability to detect multiple conductors and enhancing the system's capability to determine contact events.
Implementation Method 1
the driving circuit obtains a first capacitance value of the sensing electrode to the grounding terminal... obtains a second capacitance value of the sensing electrode to the grounding terminal, and determines whether the first conductor to-be-tested contacts the contacting conductor according to a difference value between the first capacitance value and the second capacitance value
Data Source
AI summary
A capacitance-type sensing system for indirect contact includes a capacitance-type sensor and a grounding conductor. The capacitance-type sensor includes a sensing electrode and a driving circuit electrically connected to the sensing electrode. The driving circuit has a grounding terminal. The grounding conductor is electrically connected to the grounding terminal and configured to contact a grounding surface. A contact area of the grounding conductor is greater than or equal to 3000 mm2.