In-Cell Capacitive Touch Screen Voltage Alternation
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Solution Overview
Problem
In-cell capacitive touch screen panels face issues with non-uniform image displaying and increased aging rate of liquid crystal molecules due to the higher touch driving voltage applied consecutively to common electrodes, affecting image quality and longevity.
Innovation Solution
The solution involves alternately providing touch driving voltage to odd-numbered and even-numbered touch driving electrodes within neighboring image frame display time periods, ensuring that common electrodes and touch driving electrodes receive appropriate voltages during display and touch drive time periods to maintain uniform image display and reduce liquid crystal molecule aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch driving voltage is applied to common electrodes during touch drive time period, then touch driving function is achieved, but non-uniform image displaying occurs and liquid crystal molecule aging rate increases
Solution Approach 1:
The touch driving electrodes are divided into odd-numbered and even-numbered groups. During the touch drive time period, only one group (either odd or even) receives touch driving voltage while the other group receives common electrode voltage. This segmentation allows touch driving function to be achieved in specific regions without causing non-uniform image display across the entire screen, and prevents continuous high voltage application to any single common electrode, thereby reducing liquid crystal molecule aging.
2Ease of operation
If common electrodes are provided with touch driving voltage within touch drive time period, then touch sensing is enabled, but image quality deteriorates in corresponding areas
Solution Approach 1:
The screen is segmented into different operational zones through voltage assignment. In regions where touch driving voltage is applied to touch driving electrodes, touch sensing is enabled. In regions where common electrode voltage is maintained, image display quality is preserved. This spatial segmentation allows both touch sensing and high-quality image display to coexist without mutual interference.
Solution Approach 2:
Different voltage conditions are applied to different spatial locations. Touch driving voltage is applied only to specific touch driving electrodes (odd or even numbered) in specific regions, while common electrode voltage is maintained in other regions. This local differentiation ensures that touch functionality is achieved where needed without compromising image quality in display-critical areas.
3Productivity
If common electrodes are consecutively provided with touch driving voltage, then continuous touch driving is achieved, but liquid crystal molecule aging rate increases
Solution Approach 1:
The voltage application follows a periodic pattern that alternates between touch driving voltage and common electrode voltage for different groups of touch driving electrodes across consecutive frames. In the N-th frame, odd-numbered touch driving electrodes receive touch driving voltage while even-numbered ones receive common electrode voltage. In the (N+1)-th frame, this pattern is reversed. This periodic alternation enables continuous touch driving capability while ensuring that no single common electrode is continuously exposed to high touch driving voltage, thereby extending liquid crystal molecule service life.
4Adaptability or versatility
If time division multiplex access is used on common electrodes, then both image display and touch driving functions are achieved, but non-uniform image displaying occurs in areas with touch driving voltage
Solution Approach 1:
The common electrodes are segmented into different voltage reception groups based on their spatial relationship with touch driving electrodes. Common electrodes in regions where odd-numbered touch driving electrodes receive touch driving voltage are assigned to receive common electrode voltage during those periods, while common electrodes in regions with even-numbered touch driving electrodes follow the opposite pattern. This segmentation ensures that common electrodes never simultaneously experience the voltage transitions that cause non-uniform image display, while still enabling both image display and touch driving functions through time division multiplex access.
Data Source
AI summary
The present invention discloses a driving method for an in-cell capacitive touch screen panel comprising: providing a common electrode voltage for image display to the common electrodes and each even-numbered one of the touch driving electrodes, and providing a touch driving voltage for touch driving to each odd-numbered one of the touch driving electrodes within a touch drive time period of a N-th image frame display time period; providing the common electrode voltage to the common electrodes and each odd-numbered one of the touch driving electrodes, and providing the touch driving voltage to each even-numbered one of the touch driving electrodes within a touch drive time period of a (N+1)-th image frame display time period. The present invention further provides a in cell capacitive touch screen panel.