Touch Sensing System Using Data Lines for Pen Signal Radiation
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Solution Overview
Problem
In display apparatuses with capacitance-type touch sensors, the parasitic capacitance between touch electrodes and electrode lines causes distortion of the pen uplink signal, leading to recognition issues with stylus pens, making precise pen operations unfeasible.
Innovation Solution
A touch sensing system that temporally divides a frame into display and touch driving periods, using data lines or reference voltage lines to radiate the pen uplink signal during the touch driving period, minimizing parasitic capacitance and reducing signal distortion by avoiding overlap with shield electrodes or using data lines as radiation electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pen uplink signal is radiated using the touch electrode, then the stylus pen can receive the signal, but the signal is distorted due to large parasitic capacitance between the touch electrode and electrode lines
Solution Approach 1:
The frame period is segmented into display driving periods and touch driving periods. During touch driving periods, the pen uplink signal is radiated through data lines instead of touch electrodes, avoiding parasitic capacitance issues. This temporal segmentation allows both display function and touch sensing function to operate without mutual interference.
Solution Approach 2:
Data lines are used as intermediary components to radiate the pen uplink signal during touch driving periods. Since data lines do not overlap with touch electrodes during these periods, they serve as an ideal intermediary that eliminates parasitic capacitance while still enabling signal transmission to the stylus pen.
2Device complexity
If the touch electrode is used for both display and touch signal radiation, then device complexity is reduced, but signal distortion occurs due to resistor-capacitor delay
Solution Approach 1:
The system dynamically switches the function of data lines between display driving mode and touch sensing mode based on the current period. During display driving periods, data lines supply data voltages to pixels. During touch driving periods, data lines radiate pen uplink signals. This dynamic functional switching allows existing components to serve multiple purposes without compromising signal quality.
Solution Approach 2:
The system employs periodic alternation between display driving periods and touch driving periods within each frame. This periodic action ensures that touch electrode-based touch sensing and data line-based signal radiation occur at different times, eliminating the RC delay problem while maintaining both display and touch functionality.
3Reliability
If data lines are used to radiate the pen uplink signal during touch driving period, then signal distortion is reduced, but the display function must be temporarily suspended
Solution Approach 1:
During touch driving periods, the data lines temporarily discard their display function to serve as signal radiation channels for touch sensing. After the touch driving period ends, the data lines recover their display function for the next display driving period. This temporary functional discarding and recovery enables high-quality signal transmission without permanent loss of display capability.
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 enhances pen touch performance by reducing signal distortion and ensuring reliable recognition of pen inputs, improving the accuracy and feasibility of pen operations.
Implementation Method 1
The pen uplink signal is radiated using the touch electrode of the display apparatus and is transmitted to the stylus pen
Implementation Method 2
a stylus pen configured to receive a pen uplink signal during the touch driving period and output a pen downlink signal synchronized with the pen uplink signal
Implementation Method 3
a capacitance-type touch sensor... a touch sensing circuit configured to sense voltages of the touch electrodes based on the pen downlink signal
Data Source
AI summary
A touch sensing system may include, for example, pixels for displaying an input image, data lines, touch electrodes, a timing controller for dividing one frame into a display driving period for displaying the input image and a touch driving period for driving the touch electrodes, a stylus pen for receiving a pen uplink signal during the touch driving period and outputting a pen downlink signal, and a touch sensing circuit for causing the pen uplink signal to be radiated to the stylus pen from the data lines during the touch driving period and for sensing voltages of the touch electrodes based on the pen downlink signal. In another example, a touch sensing system may supply the pen uplink signal, which is to be radiated to the stylus pen, using touch electrodes and reference voltage lines during the touch driving period. Methods of driving a touch sensing system are also disclosed.