Capacitive Sensor Matrix Switching Absolute and Transcapacitance Modes

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Solution Overview

Problem

Existing capacitive sensing technologies face limitations in efficiently switching between absolute and transcapacitance sensing modes using the same sensor electrodes, which affects the accuracy and usability of input devices like touchpads and touchscreens.

Innovation Solution

The implementation of a processing system that configures sensor electrodes to perform absolute capacitive sensing by driving a modulated signal on one electrode and transcapacitance sensing by driving a transmitter signal on another electrode, allowing for efficient switching between sensing modes using the same electrode layout.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate electrode configurations are used for absolute and transcapacitance sensing, then sensing accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvesensing accuracyVSAvoidelectrode configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor electrodes are designed to perform multiple functions by switching between absolute capacitive sensing mode and transcapacitance sensing mode. The same physical electrodes can be configured differently through signal driving methods, eliminating the need for separate electrode sets for each sensing type while maintaining sensing accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically reconfigures the electrode functionality by changing the driving signals applied to the electrodes. The processing system switches between different sensing modes by modifying how signals are driven on the electrodes, allowing flexible adaptation between absolute and transcapacitance sensing without physical reconfiguration.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multiple sensing modes are supported with separate electrode configurations, then sensing versatility is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvesensing mode versatilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

A single electrode layout is designed to support multiple sensing modes through software-controlled signal driving. The processing system implements both absolute capacitive sensing and transcapacitance sensing using the same physical electrodes, significantly simplifying manufacturing while maintaining full sensing versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If the same sensor electrodes are used for both sensing modes, then device complexity is reduced, but sensing accuracy may deteriorate

Engineering Contradiction:

Improveelectrode configuration complexityVSAvoidsensing accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system achieves high sensing accuracy with a single electrode configuration by dynamically switching between sensing modes through signal processing. The processing system optimizes signal driving for each mode, ensuring that both absolute and transcapacitance sensing maintain high precision despite using the same physical electrodes.

Inventive Principle:

Principle #15Dynamics

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 usability of input devices by improving sensing accuracy and flexibility, enabling effective detection of input objects in various modes without the need for separate electrode configurations.

Implementation Method 1

drive a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes to determine a change in absolute capacitance between the driven sensor electrode and an input object

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

drive a transmitter signal onto the first sensor electrode and measure a resulting signal on the second sensor electrode

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS9274662B2Sensor matrix pad for performing multiple capacitive sensing techniques

Publication Date: 2016.03.01 SYNAPTICS INC

AI summary

Embodiments in the present disclosure use various individual electrodes in a capacitive sensing pixel of an electrode matrix to perform two different techniques of capacitive sensing. For example, a capacitive sensing pixel may include at least two sensor electrodes that may be driven different by a processing system depending on the current capacitive technique being used to user interaction. When performing absolute capacitive sensing, a first one of the sensor electrodes may be driven with a modulated signal in order to measure a change in absolute capacitance between the driven sensor electrode and an input object. Alternatively, when performing transcapacitance sensing, the first sensor electrode is driven with a transmitter signal while a resulting signal is measured on a second sensor electrode in the capacitive pixel. In this manner, the individual electrodes in a capacitive sensing pixel may be driven differently depending on the current capacitive sensing technique.