Grouped Touch Signal Line Charging for RC Delay Reduction
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Solution Overview
Problem
Large-size touch display screens experience excessive RC delay due to increasing node capacitance and resistance, leading to incorrect calculation of touch points.
Innovation Solution
Grouping touch signal lines, charging node capacitors in each group sequentially, and discharging them through sense signal lines to determine capacitance values, allowing for simultaneous charging of node capacitors within each group, thereby reducing overall charging time and increasing RC delay tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch driving circuit charges the node capacitor in a large-size touch display screen, then the capacitance value increases continuously as the number of touch points increases, but the RC delay increases excessively leading to incorrect touch point calculation
Solution Approach 1:
The patent divides the touch signal lines into multiple groups, with each group containing multiple touch signal lines. Node capacitors within each group are charged simultaneously, while different groups are charged sequentially. This segmentation allows parallel charging operations within groups, reducing the overall charging time and RC delay for large-size touch display screens while maintaining accurate touch point calculation.
2Loss of time
If the touch driving circuit charges all node capacitors sequentially one by one, then the charging time is extended, but the RC delay increases excessively
Solution Approach 1:
The patent segments touch signal lines into multiple groups and charges node capacitors within each group simultaneously rather than sequentially. This parallel charging approach within groups significantly reduces the total charging time and RC delay, while the sequential processing of different groups maintains measurement reliability and touch point calculation accuracy.
Solution Approach 2:
The patent combines multiple touch signal lines into groups and charges all node capacitors within each group simultaneously using shared charging circuits. This merging approach enables parallel operation, reducing the overall charging time and RC delay accumulation that would occur with purely sequential charging of individual node capacitors.
3Measurement precision
If the resistance value increases as the distance of the touch driving node increases, then the RC delay increases gradually, but the touch points cannot be calculated correctly when the increase exceeds one fifth of scanning time
Solution Approach 1:
The patent segments the large-size touch display screen into multiple groups of touch signal lines. By charging node capacitors within each group simultaneously rather than sequentially, the patent reduces the effective charging time and RC delay for each segment. This segmentation strategy allows the system to handle larger distances between touch driving nodes while maintaining accurate touch point calculation within the reduced time window.
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 method effectively saves charging time, increases charging time for each group of touch signal lines, and enhances the touch screen's ability to accurately determine touch point positions, even under greater RC delay conditions.
Implementation Method 1
a node capacitor C would increase continuously as the number of the touch points increases
Implementation Method 2
a projected capacitive touch mainly utilizes capacitive sensing formed due to a contact between transparent electrodes on the touch screen and fingers of humans or conductive objects
Implementation Method 3
a resistance value R would increase continuously as a distance of the touch driving node increases. Therefore, in the process of touch driving of the touch screen, the corresponding RC delay would increase gradually
Data Source
Figure 1~2b
Figure 3
Figure 4~5
AI summary
There are disclosed a driving method of a touch screen, the touch screen and a display apparatus. The driving method comprises: taking at least two touch signal lines as a group and charging node capacitors included in each group of touch signal lines sequentially; discharging the node capacitors included in each touch signal line of the group of touch signal lines through the respective sense signal lines sequentially and determining capacitance value of each node capacitor; and determining coordinates of touch points on the touch screen according to determined capacitance value of each node capacitor. Thus, the node capacitors included in a group of touch signal lines on the touch screen are charged simultaneously by taking a group as a unit. Compared with a traditional touch screen that charges the node capacitor in only one touch signal line at each time, the driving method saves the charging time of the touch signal lines on the entire touch screen effectively, meanwhile can increase the charging time of each group of touch signal lines, and further can increase the charging time of the node capacitors included in respective touch signal lines, so that the touch screen is capable of tolerating a greater RC delay value.