Partitioned Common Electrodes for In-Cell Touch Display Driving
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Solution Overview
Problem
In display devices with in-cell capacitive touch panels, the load on touch panel scan electrodes becomes heavy due to the intersection of video signal lines with touch panel scan electrodes, leading to inefficiencies in both touch sensing and video signal driving.
Innovation Solution
The configuration includes partitioned common electrodes acting as touch panel scan electrodes, which extend in the direction perpendicular to gate lines, allowing for alternate repetition of write periods and touch sensing periods, and adjustable signal polarity inversion cycles for drain lines to optimize touch sensing and reduce electric field leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If common electrodes extend in the direction of scan lines, then touch panel scan function is achieved, but load on touch panel scan electrodes becomes heavy
Solution Approach 1:
The common electrodes are partitioned into multiple regions along the scan line direction, with each region serving as a separate touch panel scan electrode. This segmentation reduces the capacitive load on each individual scan electrode, allowing for effective touch sensing while reducing overall power consumption compared to a single continuous electrode configuration.
2Ease of operation
If common electrodes are partitioned and used as touch panel scan electrodes, then touch sensing is enabled, but video signal driving efficiency decreases
Solution Approach 1:
The system alternates between video signal writing periods and touch sensing periods in a periodic manner. During video writing periods, the common electrodes receive video signals; during touch sensing periods, they function as scan electrodes. This time-division multiplexing allows both functions to operate effectively without interfering with each other's performance.
Solution Approach 2:
The signal polarity of drain lines for specific color subpixels is inverted at cycles shorter than one frame, and this inversion cycle can be adjusted. By optimizing the polarity inversion timing and cycle, the system maintains effective video signal writing while accommodating the dual-function requirement of the common electrodes.
3Measurement precision
If signal polarity inversion cycle is shortened, then touch sensing accuracy improves, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the signal polarity inversion cycle based on operating conditions. The inversion cycle can be set to values shorter than one frame when high touch sensing accuracy is required, and adjusted to longer cycles when power consumption needs to be reduced. This dynamic adaptability allows optimization of the trade-off between touch sensing performance and power consumption.
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 configuration reduces the load on touch panel scan electrodes, enhances touch sensing accuracy, and minimizes power consumption while maintaining high-impedance driving, enabling faster writing and larger screen sizes with reduced recognition of block unevenness.
Implementation Method 1
a liquid crystal layer 30 between the array substrate 10 and the counter substrate 20
Implementation Method 2
capacitive touch panels for the input function are being more and more introduced into liquid crystal display devices
Data Source
AI summary
A display device comprises gate lines extending in a first direction, drain lines extending in a second direction, common electrodes extending in the second direction, and a drive circuit. The common electrodes are configured to be partitioned over drain lines of pixels of a specific color and to be used also as touch panel scan electrodes. The drive circuit is configured so that write periods for driving the gate lines and touch sensing periods for driving the scan electrodes are alternately repeated in each frame period, signal polarity of drain lines for colors other than the specific color is inverted every frame, signal polarity of drain lines for the specific color is inverted at a cycle shorter than one frame, and the cycle of the signal polarity inversion of the drain lines for the specific color can be changed.