Large Matrix Touchscreen Double Injection Electronics

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Solution Overview

Problem

Large-scale projected capacitive touch matrices face issues with sensitivity loss at row ends due to resistivity and capacitance increases, leading to poor performance and the need for juxtaposing multiple screens, which introduces central discontinuities affecting image perception.

Innovation Solution

A device with a touchscreen matrix where each row generates and receives synchronous transmission signals at both ends, using demodulation and calibration to accurately detect touch positions and differentiate between true and phantom touches, and to identify cuts in the matrix.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the matrix touch surface uses large dimensions with increased number of rows and columns, then the coverage area increases, but the scanning time becomes too long and sensitivity is lost at row ends

Engineering Contradiction:

Improvetouch surface areaVSAvoidscanning time

Core Design Contradiction:

Area of stationary objectVSLoss of time

Solution Approach 1:

The patent divides the large touch matrix into smaller sub-matrices or scanning zones. Each sub-matrix can be scanned independently and simultaneously, allowing parallel processing of multiple regions. This segmentation reduces the total scanning time while maintaining full coverage of the large touch surface area.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If the matrix touch surface uses large dimensions with increased number of rows and columns, then the coverage area increases, but sensitivity is lost at row ends due to resistivity and capacitance increases

Engineering Contradiction:

Improvetouch surface areaVSAvoidtouch detection sensitivity

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent applies different signal characteristics or scanning parameters to different regions of the matrix. Specifically, it uses orthogonal frequencies that are locally optimized for different zones, ensuring that each region maintains adequate signal strength and sensitivity despite variations in resistivity and capacitance across the large surface area.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the frequency parameter of the sinusoidal signals used for scanning. By using multiple orthogonal frequencies simultaneously, the system can compensate for signal attenuation and sensitivity loss at distant row ends, as different frequencies interact differently with the resistive and capacitive properties of the conductive materials.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If two matrix touchscreens are juxtaposed to form a double-size touchscreen, then the overall coverage area increases, but a central discontinuity appears affecting image perception

Engineering Contradiction:

Improvetouch surface areaVSAvoidimage continuity

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent merges multiple sub-matrices or scanning zones into a single unified coordinate system. By continuously scanning across the entire large matrix using orthogonal frequencies, the system eliminates the discontinuity that would arise from juxtaposing separate screens, providing seamless image perception across the full touch surface area.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables accurate detection and positioning of touches on large touchscreens without central discontinuities, effectively eliminating phantom touches and facilitating the detection and location of cuts, ensuring reliable operation even in critical systems like avionics.

Implementation Method 1

The general principle of operation of a matrix touch surface of 'projected capacitive' type consists in measuring the capacitance variations caused by the touches that are to be detected.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

One of the standard modes is to inject sinusoidal signals at particular frequencies. This method offers the advantage of minimising the radiated emissions

Methodology Applied

Scientific EffectSinusoidal signal generation:

Implementation Method 3

the first transmission signal and the second transmission signal being synchronous, having the same frequency, the same amplitude and the same phase

Methodology Applied

Scientific EffectSynchronous signal transmission:

Data Source

PatentUS10331269B2Matrix touch surface of large dimensions comprising double injection electronics of the rows or of the columns

Publication Date: 2019.06.25 THALES SA

AI summary

A device with touch surface with projected capacitive detection comprising a matrix touchscreen comprises a plurality of conductive rows and of conductive columns, the screen linked to electronic control means generating, for each conductive row and for each conductive column, transmission signals and electronic means for receiving and analyzing the reception signals from each conductive row and from each conductive column. Each row of the device comprises, at one of its ends, first means for generating a first transmission signal and first means for receiving a first reception signal and, at its opposite end, second means for generating a second transmission signal and second means for receiving a second reception signal, the first transmission signal and the second transmission signal being synchronous, having the same frequency, the same amplitude and the same phase.