Capacitive Button Threshold Adjustment for Glove Detection

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Solution Overview

Problem

Capacitive-sensing devices face challenges in accurately detecting actuations by both bare fingers and fingers covered with gloves due to the limitations of fixed threshold sensitivity settings, which are not adaptable to different types of actuation methods.

Innovation Solution

The capacitive-sensing device dynamically adjusts its actuation detection threshold based on temperature measurements from an infrared sensor and proximity signals, allowing for adaptive sensitivity settings between low and high sensitivity thresholds depending on whether a bare finger or a gloved finger is used, ensuring optimal detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a fixed threshold sensitivity setting is used for capacitive sensing, then the device structure remains simple, but the detection accuracy deteriorates when different types of actuation (bare finger vs. gloved finger) are used

Engineering Contradiction:
Improvedetection accuracyVSAvoidsensitivity adjustment mechanism
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements dynamic threshold adjustment by detecting the temperature of the actuating object. The system automatically adapts the sensitivity threshold based on whether the object is warm (bare finger) or cold (gloved finger), transforming a static system into a dynamic one that responds to environmental conditions

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the sensitivity parameter (threshold value) based on temperature detection. By measuring the temperature of the actuating object and adjusting the threshold accordingly, the system optimizes detection accuracy for different actuation types without requiring complex mechanical adjustments

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the detection threshold is set to be sensitive enough for bare fingers, then bare finger actuation is detected accurately, but false detections increase when gloved fingers are used

Engineering Contradiction:
Improvebare finger detection accuracyVSAvoidfalse detection
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces feedback through temperature detection. The system continuously monitors the temperature of the actuating object and uses this information to adjust the detection threshold in real-time, preventing false detections by adapting to the actual actuation conditions

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the detection threshold parameter based on temperature measurements. When a cold object (gloved finger) is detected, the threshold is adjusted to prevent false positives, while maintaining high sensitivity for warm objects (bare fingers)

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the detection threshold is set to be less sensitive to accommodate gloved fingers, then gloved finger actuation is detected, but detection accuracy deteriorates for bare finger actuation

Engineering Contradiction:
Improvegloved finger detection accuracyVSAvoidmissed detection
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent makes the detection threshold dynamic rather than fixed. By continuously adapting the threshold based on temperature feedback, the system can optimize sensitivity for each specific actuation event, preventing missed detections while avoiding false positives

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent adjusts the detection threshold parameter based on temperature measurements. When a warm object (bare finger) is detected, the threshold is lowered to ensure accurate detection, while for cold objects (gloved fingers), the threshold is raised to maintain detection accuracy

Inventive Principle:
Principle #35Parameter 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

This adaptive threshold adjustment significantly improves the detection accuracy of capacitive-sensing buttons by tailoring sensitivity to the specific type of actuation, enhancing user interaction in various environmental conditions.

Implementation Method 1

The actuation acts to alter a capacitance charge value of the capacitive-sensing button. The actuation detection electrical circuit has a threshold value and it outputs a button actuation signal when its capacitance charge value exceeds the threshold value.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

The proximity sensor generates a proximity signal when an object is placed in an area that is near the capacitive-sensing button.

Methodology Applied
Scientific EffectProximity sensing: Capacitance

Implementation Method 3

The intra-red temperature sensor measures a temperature of this nearby area and it often uses infra-red techniques for the measurement.

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Data Source

PatentEP2855210B1Glove detection/adjustment of sensitivity for capacitive sensing button and slider elements
Publication Date: 2020.08.05 CONTINENTAL AUTOMOTIVE GMBH
  • EP2855210B1 patent drawingFigure 1
  • EP2855210B1 patent drawingFigure 2
  • EP2855210B1 patent drawingFigure 3

AI summary

The application provides an input device for a control system of a vehicle. The input device includes at least one capacitive-sensing button, an actuation detection electrical circuit, a proximity sensor, a proximity temperature sensor, and a processor. In use, the capacitive-sensing button receives an actuation from a user. The actuation alters a capacitance value of the button. The detection electrical circuit comprises a threshold value and it outputs a button actuation signal when the capacitance value exceeds the threshold value. The proximity sensor generates a proximity signal when an object is provided near the capacitive-sensing button. The proximity temperature sensor provides a temperature measurement of the nearby area. The processor adjusts the threshold value to an adjustment value that is derived from the comparison signal.