In-Cell Touch Panel Pause Period Control for Stable Reporting

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Solution Overview

Problem

In display devices with built-in in-cell touch sensors, variable low frame rate driving causes a decrease in touch position reporting rate due to abnormal operations when the existing driver IC fails to handle changing pause periods effectively.

Innovation Solution

A display device configuration that includes sensor electrodes, a control unit, analog front ends, and a coordinate calculation unit, which repeats touch position detection at a predetermined interval until a vertical synchronization signal is input, allowing for the extension of the pause period and smooth transition between normal and pause periods, thereby preventing abnormal operations and maintaining a stable reporting rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If variable low frame rate driving is implemented by changing pause period length, then power consumption is reduced and frame rate is optimized, but touch position reporting rate decreases due to driver IC algorithm failure

Engineering Contradiction:

Improvepower consumptionVSAvoidtouch position reporting rate

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent implements dynamic adjustment of the pause period length based on whether image data is received from the host. When image data is received, the pause period is set to a first length; when no image data is received, it is set to a second length. This dynamic adaptation allows the system to optimize power consumption while maintaining touch position reporting functionality under varying operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of pause period length to resolve the contradiction. By switching between a first pause period length (when image data is received) and a second pause period length (when no image data is received), the system maintains appropriate timing for touch position detection and reporting, preventing algorithm failure in the driver IC while still achieving power savings through low frame rate driving.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by stationary object

If pause period length is extended for power saving, then power consumption decreases, but touch position detection timing becomes misaligned causing abnormal operations

Engineering Contradiction:

Improvepower consumptionVSAvoidtouch position detection accuracy

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent dynamically changes the pause period parameter based on operational conditions. When image data is received from the host, a first pause period length is used; when no image data is received, a second pause period length is used. This parameter adaptation ensures that touch position detection timing remains synchronized with the display refresh cycle, preventing detection failures while maintaining power efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses feedback from the host regarding image data reception status to adjust the pause period length. This feedback mechanism allows the system to adapt its timing parameters in real-time, ensuring that touch position detection occurs at appropriate intervals regardless of whether the display is actively updating, thereby maintaining detection reliability while optimizing power consumption.

Inventive Principle:

Principle #23Feedback

3Device complexity

If existing driver IC is used with variable pause periods, then device complexity is reduced, but algorithm failure occurs causing touch position transmission to fail

Engineering Contradiction:

Improvecontrol circuit complexityVSAvoidtouch position transmission reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the timing parameters (pause period lengths) to work within the constraints of the existing driver IC algorithm. By carefully selecting and switching between a first and second pause period length based on image data reception status, the system maintains compatibility with the fixed algorithm in the driver IC, preventing algorithm failure while still enabling variable low frame rate driving functionality.

Inventive Principle:

Principle #35Parameter changes

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

The solution effectively prevents a decrease in touch position reporting rate during variable low frame rate driving by ensuring continuous detection and accurate coordinate specification, even when pause periods are extended, thus maintaining a stable and efficient touch position reporting mechanism.

Implementation Method 1

the position of an object to be detected such as a finger of a user (operator) or a touch pen is detected based on a change in capacitance

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11209932B2Display device with built-in touch panel and driving method therefor

Publication Date: 2021.12.28 SHARP KK

AI summary

A display device can extend a pause period by using a preset second setting period as a unit when a length of the pause period exceeds the second setting period. Further, detection of a touch position and specification of coordinates are interrupted when a vertical synchronization signal is received while specifying the coordinates of the touch position, and coordinates remaining in a coordinate calculation unit are discarded.