In-Cell Touch Display Image Sticking Elimination
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Solution Overview
Problem
In-cell touch displays experience image sticking due to accumulated charges caused by differences in resistance and capacitance in the charge/discharge routes of touch sensing electrodes, leading to voltage disparities and parasitic charge accumulation.
Innovation Solution
The method involves dividing touch sensing electrodes into at least two sets and applying different voltages to each set during non-display periods, alternating the electric-field direction to cancel out charge accumulation effects, by controlling the voltage pins to ensure one set receives a higher voltage than the other for preset periods, effectively reducing image sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch sensing electrodes are connected to different pins with different route lengths, then touch sensing function is achieved, but image sticking occurs due to RC delay differences
Solution Approach 1:
The patent applies periodic voltage inversion to the common electrode during non-display periods. By alternately applying positive and negative voltages in a periodic manner, the method compensates for the RC delay differences caused by different route lengths, preventing charge accumulation and eliminating image sticking while maintaining touch sensing functionality.
Solution Approach 2:
The patent changes the voltage parameter of the common electrode dynamically. During non-display periods, the voltage polarity is inverted between different groups of touch sensing electrodes, creating controlled voltage differences that compensate for the resistance and capacitance variations in different charge/discharge routes, thereby resolving the image sticking issue.
2Adaptability or versatility
If common voltage electrode is cut into multiple touch sensing electrodes, then touch sensing capability is enabled, but parasitic charges accumulate causing image sticking
Solution Approach 1:
The patent employs periodic voltage inversion during non-display periods to alternately charge and discharge different groups of touch sensing electrodes. This periodic action prevents parasitic charges from accumulating at any single electrode by systematically reversing the voltage polarity, thereby eliminating the harmful charge accumulation effect while preserving touch sensing capability.
Solution Approach 2:
The patent converts the harmful effect of RC delay differences and charge accumulation into a beneficial compensation mechanism. By deliberately applying voltage differences between electrode groups during non-display periods, the method uses the same electrical parameters that cause the problem to create a compensating effect that eliminates image sticking.
3Stability of the object's composition
If voltage is held constant for prolonged time, then stable display is maintained, but image sticking phenomenon occurs
Solution Approach 1:
The patent introduces periodic voltage inversion during non-display periods to counteract the stabilizing effect that causes image sticking. By alternately inverting the voltage polarity on different electrode groups, the method prevents the liquid crystal molecules from maintaining a fixed orientation for prolonged periods, thereby eliminating image sticking while preserving display stability during active display periods.
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 cancels out charge accumulation and reduces the image sticking phenomenon by continuously switching the electric-field direction between sets of touch sensing electrodes, improving display performance.
Implementation Method 1
An intensity of an electric field between the electrodes can be changed by configuring a voltage between the two electrodes. The intensity of the electric field makes the molecules in the liquid crystal unit present a specific direction (i.e., parallel to or perpendicular to the electric field, or at a certain angle therebetween) with respect to the intensity of the electric field.
Implementation Method 2
Because the first charge/discharge route R1 and the second charge/discharge route R2 have different lengths, the resistance of the first charge/discharge route R1 is different from the resistance of the second charge/discharge route R2. An equivalent capacitance of the first touch sensing electrode 201 with respect to the ground may be regarded as the same as an equivalent capacitance of the second touch sensing electrode 202 with respect to the ground.
Implementation Method 3
Thus, the resistor-capacitor (RC) delay composed of the first charge/discharge route R1 and a first common electrode 201 is longer than the RC delay composed of the second charge/discharge route R2 and a second common electrode 202.
Data Source
AI summary
A method for eliminating image sticking of an in-cell touch display and a mobile device using the same are provided. The method comprises the steps of: providing at least a first common electrode and a second common electrode in the in-cell touch display to perform touch sensing, wherein the first common electrode is electrically connected to a first pin of a touch control circuit through a first charge/discharge route, the second common electrode is electrically connected to a second pin of the touch control circuit through a second charge/discharge route; and in a time except for display time, controlling the first pin and the second pin so that a voltage of the first pin is higher than a voltage of the second pin for at least a first preset period, and then controlling the first pin and the second pin so that a voltage of the second pin is higher than the voltage of the first pin for at least the first preset period.