Capacitive Sensor Ground Element for Noise Drainage

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Solution Overview

Problem

Capacitive sensing technologies face challenges in accurately detecting the presence and position of conductive objects due to noise signals that mix with useful capacitance signals, leading to reduced signal-to-noise ratios and increased measurement rechecking and power consumption.

Innovation Solution

Incorporating a ground element in capacitive sensor scan regions, which is coupled to a grounded capacitive sensor element not being scanned, provides a pathway for noise signals to be drained to ground, improving the signal-to-noise ratio and reducing the need for rechecking measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive sensing is used to detect conductive objects, then presence and position detection capability is provided, but noise signals mix with capacitance signals reducing signal-to-noise ratio

Engineering Contradiction:

Improvepresence detection accuracyVSAvoidnoise signal interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The sensor array is divided into multiple independently controllable sensor elements that can be scanned sequentially. By activating only one sensor element at a time and grounding others, the system segments the measurement process to isolate and eliminate noise sources while maintaining detection capability across the entire array.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A ground element is introduced as an intermediary component between the active sensor element and the grounding system. This ground element provides a controlled pathway for noise signals to be drained to ground, acting as a mediator that separates useful capacitance signals from harmful noise without interfering with the detection function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If noise signals are not drained, then signal processing is simpler, but measurement rechecking increases and power consumption rises

Engineering Contradiction:

Improvemeasurement stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful noise signals into a beneficial outcome by providing a controlled drainage path through the ground element. The noise signals that would otherwise corrupt measurements and require rechecking are instead directed to ground, transforming them from a problem into a solution that improves measurement reliability while reducing power consumption.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system implements a feedback mechanism where the state of sensor elements (active or grounded) is dynamically controlled based on the scanning sequence. This feedback control ensures that at any given time, the appropriate elements are activated while others are grounded, automatically adjusting the system state to maintain optimal signal-to-noise ratio and measurement stability.

Inventive Principle:

Principle #23Feedback

3Area of stationary object

If all sensor elements are actively scanned simultaneously, then detection coverage is maximized, but noise interference and power consumption increase

Engineering Contradiction:

Improvedetection coverage areaVSAvoidnoise signal interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The simultaneous scanning of all sensor elements is segmented into sequential scanning of individual elements or small groups. This temporal segmentation allows the system to maintain full detection coverage over the sensor array area while reducing instantaneous noise interference and power consumption by activating only necessary elements at each moment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor elements are scanned in a periodic sequence rather than simultaneously. Each sensor element is activated for a brief period, then grounded while the next element is activated. This periodic action pattern maintains comprehensive detection coverage across the entire array while ensuring that at any instant, noise interference and power consumption are minimized by having only one or a few elements active.

Inventive Principle:

Principle #19Periodic action

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 approach enhances the accuracy of presence detection and position calculation, reduces measurement rechecking, and leads to faster processing and lower power consumption by stabilizing capacitance signals.

Implementation Method 1

the ground element is coupled to a capacitive sensor element not being scanned with an applied voltage through a capacitance

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS9612265B1Methods and apparatus to detect a conductive object

Publication Date: 2017.04.04 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

A method and apparatus scan a first capacitive sensor element that is located in a first scan region for a presence of a conductive object and then scan a second capacitive sensor element that is located in a second scan region for the presence of the conductive object. The scan of the first capacitive sensor element includes applying a ground voltage to a ground element through the second capacitive sensor element, the ground element located in the first scan region.