Capacitive Sensor Electrode Layout for Unintended Touch Rejection
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Solution Overview
Problem
Conventional non-contact sensors react to unintended user operations due to overlapping detection ranges, leading to ineffective operation of apparatuses.
Innovation Solution
A non-contact sensor design featuring a first electrode, a second electrode, and a third electrode with a determination circuit that detects changes in electrostatic capacitance to differentiate between intended and unintended target interactions, using a third electrode with a more negative electric potential to create distinct detection regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single electrode is used for non-contact detection, then the detection range is large and coverage is good, but the sensor cannot distinguish between intended and unintended operations
Solution Approach 1:
The single electrode is divided into multiple electrodes (first electrode, second electrode, third electrode) with different detection regions. Each electrode monitors a specific area, allowing the system to distinguish between intended operations (target in first region only) and unintended operations (target in second region or multiple regions simultaneously), thus resolving the contradiction between broad detection coverage and operation discrimination accuracy
Solution Approach 2:
Different electrodes are assigned different detection regions and functions. The first electrode's detection region is designed to be surrounded by the second electrode's detection region, creating distinct spatial zones. This local differentiation allows the sensor to identify the position and intent of the target based on which specific electrode detects the change, maintaining good coverage while enabling precise operation discrimination
2Measurement precision
If multiple electrodes with overlapping detection regions are used, then operation discrimination is improved, but the device complexity increases
Solution Approach 1:
The detection regions are arranged in a nested configuration where the first detection region is surrounded by the second detection region. This nested structure allows for clear spatial differentiation and simple logical judgment in the determination circuit: if the target is detected only in the inner region, it's an intended operation; if detected in the outer region or both regions, it's an unintended operation. This nesting approach achieves precise operation discrimination without requiring complex electrode arrangements
Solution Approach 2:
Instead of having the first electrode's detection region surround the second electrode's region, the patent inverts this arrangement so that the second electrode's detection region surrounds the first electrode's region. This inverted nested configuration simplifies the determination logic and makes it easier to distinguish between intended and unintended operations, thereby reducing device complexity while maintaining high measurement precision
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
Prevents the sensor from reacting to unintended operations by accurately distinguishing between intended and unintended target interactions, ensuring only intended operations trigger the sensor's response.
Implementation Method 1
detects entry of the target into a first region by detecting a change of first electrostatic capacitance, which is electrostatic capacitance of the first electrode
Implementation Method 2
detects entry of the target into a second region by detecting a change of second electrostatic capacitance, which is electrostatic capacitance of the second electrode
Data Source
AI summary
A sensor for detecting a target in a non-contact manner includes a first electrode; a second; a third electrode that is disposed between the first electrode and the second electrode; and a determination circuit that, in operation, detects entry of the target into a first region by detecting a change of first electrostatic capacitance, which is electrostatic capacitance of the first electrode, and detects entry of the target into a second region by detecting a change of second electrostatic capacitance, which is electrostatic capacitance of the second electrode. An electric potential of the third electrode is more negative than electric potentials of the first electrode and the second electrode. At least a part of the second region at least partially surrounds an outer edge of the first region in plan view.