Touch Screen Driving Signal Transmission During Display Blanking Intervals

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Solution Overview

Problem

Existing touch screens experience electromagnetic interference during display line updates, which affects touch sensing accuracy and timing awareness, particularly due to the overlap of touch driving and display line updating signals.

Innovation Solution

A touch sensitive method and apparatus that transmit driving signals during blanking intervals and measure these signals using sensing electrodes to detect objects, incorporating pseudo-random number codes and adjusting signal parameters based on electrode distance to reduce interference and improve detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If touch sensing is performed during display line updates, then touch detection can occur continuously, but electromagnetic interference from pixel update voltages degrades sensing accuracy

Engineering Contradiction:

Improvetouch detection continuityVSAvoidtouch sensing accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the touch sensing operation into two distinct phases: sensing during active display line periods (when no driving signals are transmitted) and signal transmission during blanking intervals. This temporal segmentation separates the conflicting operations of display updating and touch sensing, allowing both to occur without mutual interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system employs periodic transmission of driving signals during blanking intervals, which occur regularly between display line updates. This periodic action allows touch sensing to occur continuously while maintaining display performance, as the sensing operations are synchronized with the periodic blanking intervals of the display refresh cycle.

Inventive Principle:

Principle #19Periodic action

2Reliability

If driving signals are transmitted during active display lines, then touch detection is enhanced, but interference with display line updates increases

Engineering Contradiction:

Improvetouch detection reliabilityVSAvoidelectromagnetic interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the touch signal transmission operation from the active display line period and relocates it to the blanking interval. This extraction removes the source of electromagnetic interference from the critical display updating period, thereby eliminating the harmful interference while maintaining touch detection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The blanking interval serves as an intermediary time period that mediates between the display updating operation and the touch sensing operation. By utilizing this intermediate period for signal transmission, the system allows both operations to coexist without direct conflict, as the blanking interval naturally provides electrical isolation from the active display lines.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If touch sensing operates independently of display timing, then sensing flexibility is improved, but timing awareness and coordination with display updates are lost

Engineering Contradiction:

Improvesensing operation flexibilityVSAvoidtiming information

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The touch sensing system incorporates feedback from the display timing signals to synchronize its operations. The sensing controller receives timing information about blanking intervals and adjusts its signal transmission accordingly, ensuring that sensing operations are coordinated with display updates while maintaining operational flexibility within the constrained time windows.

Inventive Principle:

Principle #23Feedback

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 electromagnetic interference and enhances the ability to detect touch or proximity events during display line updates, allowing for more reliable touch control and timing information acquisition.

Implementation Method 1

mutual capacitive sensing can be used to sense any external conductive object

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

transmitting a driving signal via a first driving electrode of a touch screen

Methodology Applied

Scientific EffectElectrical signal transmission: Conduction (electrical)

Data Source

PatentUS10268327B2Touch sensitive method, apparatus and electronic system for reducing interferences from pixel update

Publication Date: 2019.04.23 EGALAX EMPIA TECH INC

AI summary

The present invention provides a touch sensitive method including: transmitting a driving signal via a first driving electrode of a touch screen during a first blanking interval; and sensing the driving signal via a plurality of sensing electrodes of the touch screen during the first blanking interval for detecting an external conductive object on or near the first driving electrode.