In-Cell Matrix Sensor Excitation for Lower Background Capacitance

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Solution Overview

Problem

Existing capacitive sensing devices face challenges in reducing background capacitance between sensor electrodes and metal routing lines, which affects the accuracy and reliability of input detection.

Innovation Solution

The method involves modulating sensor electrodes in a vertical column uniformly to reduce background capacitance by maintaining the same voltage potential along each column, thereby minimizing capacitive interference from metal routing lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If sensor electrodes are modulated differently in vertical columns, then measurement flexibility is improved, but background capacitance between sensor electrodes and metal routing lines increases

Engineering Contradiction:

Improvemeasurement flexibilityVSAvoidbackground capacitance

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies equipotentiality by modulating all sensor electrodes in a vertical column to the same voltage potential simultaneously. This creates equipotential columns that reduce the electric field differential between adjacent routing lines, thereby minimizing parasitic capacitance coupling. The technique maintains measurement flexibility through code division multiplexing while ensuring uniform potential distribution within each column to reduce background capacitance interference.

Inventive Principle:

Principle #12Equipotentiality

2Measurement precision

If background capacitance is reduced by uniform column modulation, then measurement precision is improved, but device complexity increases due to coordinated excitation requirements

Engineering Contradiction:

Improveinput detection accuracyVSAvoidcoordinated excitation control

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the sensor electrode array into multiple vertical columns, each independently modulated with identical waveforms. This segmentation allows the complex coordinated excitation to be broken down into simpler, identical operations repeated across columns. The segmentation approach reduces the overall control complexity by creating modular, repeatable excitation patterns while maintaining the precision benefits of uniform column modulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses copying by replicating the same modulation waveform across all sensor electrodes within each vertical column. Instead of designing complex unique waveforms for each electrode, the system copies a standardized excitation pattern to all electrodes in a column, significantly reducing the complexity of excitation control while achieving the desired equipotential effect for improved measurement precision.

Inventive Principle:

Principle #26Copying

3Productivity

If code division multiplexing is used to excite multiple columns, then productivity is improved, but signal interference increases requiring complex separation techniques

Engineering Contradiction:

Improvemeasurement throughputVSAvoidsignal interference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements periodic action through code division multiplexing, where multiple columns are excited in periodic sequences using orthogonal or pseudo-random codes. Each column receives periodic excitation bursts separated by time intervals, allowing multiplexed operation that increases productivity. The periodic structure enables systematic signal separation at the receiver, reducing interference through correlation-based decoding techniques.

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 effectively reduces background capacitance, enhancing the accuracy and reliability of input detection in capacitive sensing devices by ensuring consistent voltage potential across sensor electrodes.

Implementation Method 1

changes in capacitive coupling that may then be used to determine positional information

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS10466848B2CDM excitation on full in-cell matrix sensor array with reduced background capacitance

Publication Date: 2019.11.05 OMNIVISION TDDI ONTARIO LLP

AI summary

Embodiments described herein include a method for detecting a presence of an input in a capacitive sensing device that includes a sensing region and a plurality of sensor electrodes. The method includes driving a first column of transmitter sensor electrodes at a first potential and driving a second column of transmitter sensor electrodes at a second potential different than the first potential. The method includes acquiring a measurement from each row of sensor electrodes, where a first sensing node includes the first column of transmitter sensor electrodes and a third column of receiver sensor electrodes, and a second sensing node includes the second column of transmitter sensor electrodes and a fourth column of receiver sensor electrodes. The method also includes determining, using the measurements from each row of sensor electrodes, a first set of transcapacitive measurements corresponding to the plurality of sensor electrodes.