Touch Sensor Noise Reduction via Periodic Sensing in Displays

Solution Overview

Problem

The existing display devices with combined display and touch sensor units face challenges in achieving high sensing accuracy and smooth input due to noise interference when the touch sensor unit operates during display image rewriting, particularly at high frame frequencies.

Innovation Solution

A display device with a gate driver that separately drives pixel groups using shift registers, allowing the touch sensor unit to operate during periods when the gate drivers are stopped, and an application processor that determines image changes to optimize touch sensing operations while minimizing noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the touch sensor unit performs sensing operation at the time when the display unit rewrites a display image, then the sensing operation can be performed continuously, but the sensing accuracy of the touch sensor unit deteriorates due to noise

Engineering Contradiction:

Improvesensing operation frequencyVSAvoidsensing accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent implements periodic sensing operations that are synchronized with the display refresh cycle. The touch sensor unit performs sensing at specific intervals (e.g., every other frame or during specific phases of the display refresh), rather than continuously. This periodic operation allows the system to balance between maintaining smooth input responsiveness and avoiding noise interference during display image rewriting, thereby resolving the contradiction between sensing operation frequency and sensing accuracy.

Inventive Principle:

Principle #19Periodic action

2Speed

If the display unit rewrites display image frequently (60 Hz frame frequency), then the display refresh is smooth, but the touch sensor unit experiences noise interference that reduces sensing accuracy

Engineering Contradiction:

Improveframe frequencyVSAvoidsensing accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent implements periodic sensing operations that are synchronized with the display refresh cycle. The touch sensor unit performs sensing at specific intervals (e.g., every other frame or during specific phases of the display refresh), rather than continuously. This periodic operation allows the system to balance between maintaining smooth input responsiveness and avoiding noise interference during display image rewriting, thereby resolving the contradiction between sensing operation frequency and sensing accuracy.

Inventive Principle:

Principle #19Periodic action

3Ease of operation

If the touch sensor unit operates during display image rewriting, then the system can maintain high responsiveness, but power consumption increases due to simultaneous operation of both units

Engineering Contradiction:

Improveinput responsivenessVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic sensing operations that are synchronized with the display refresh cycle. The touch sensor unit performs sensing at specific intervals (e.g., every other frame or during specific phases of the display refresh), rather than continuously. This periodic operation allows the system to balance between maintaining smooth input responsiveness and avoiding noise interference during display image rewriting, thereby resolving the contradiction between sensing operation frequency and sensing accuracy.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts the sensing operation timing based on the display refresh state. The system can switch between different sensing modes (e.g., sensing during display refresh, sensing after display refresh, or sensing every other frame) depending on the current operational requirements. This dynamic adjustment allows the system to optimize power consumption while maintaining input responsiveness.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20240321231A1Display Device and Operating Method Thereof

Publication Date: 2024.09.26 SEMICON ENERGY LAB CO LTD

AI summary

A display device that achieves both high-accuracy sensing by a touch sensor unit and smooth input using the touch sensor unit is provided. The display device includes a display unit and the touch sensor unit. The touch sensor unit performs touch sensing operation at a different timing from display image rewriting by the display unit, whereby the high-accuracy sensing can be achieved. The display unit has a function of rewriting a display image only in a region that needs to be rewritten. In the case where the entire display region is not necessarily rewritten, the time for the sensing operation by the touch sensor unit can be lengthened, whereby the smooth input can be achieved.