Touch Controller Timing and Polarity Switching for Display Noise
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Solution Overview
Problem
Touch sensing devices experience reduced sensitivity due to noise interference from display operation, leading to degradation in image quality.
Innovation Solution
The touch controller performs touch sensing in synchronization with display timing signals, alternating the polarity of the driving signal with each display frame or frame set to minimize noise interference and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If touch sensing is performed simultaneously with display operation, then touch sensing can be continuously monitored, but display noise reduces touch sensing sensitivity
Solution Approach 1:
The patent implements periodic touch sensing operations that are synchronized with display timing signals. Touch sensing is performed during specific time windows (e.g., during horizontal blanking periods or vertical retrace periods) rather than continuously, allowing the system to maintain touch monitoring capability while avoiding periods when display switching activity generates noise. This periodic scheduling resolves the contradiction by making touch sensing continuous over time while discrete at any given moment.
Solution Approach 2:
The patent uses display timing signals (such as VSYNC or HSYNC) as trigger events to initiate touch sensing operations at predetermined optimal moments. By preliminarily establishing the synchronization mechanism and using display timing signals to trigger touch sensing, the system ensures that touch sensing always occurs at the most favorable moments in the display cycle when noise is minimized, thereby maintaining sensitivity while preserving continuity.
2Device complexity
If touch driving signal polarity is kept constant, then touch sensing operation is simplified, but image quality degrades due to noise accumulation
Solution Approach 1:
The patent implements periodic reversal of the touch driving signal polarity, alternating between positive and negative polarities in successive time periods. This periodic polarity reversal prevents noise accumulation by ensuring that any DC offset or low-frequency interference averages out over time, thereby maintaining image quality. The systematic alternation follows a regular pattern that simplifies control while effectively managing noise.
Solution Approach 2:
The patent changes the polarity parameter of the touch driving signal in a systematic manner, alternating between +V and -V levels. This parameter change is implemented by inverting the sign of the driving voltage applied to touch electrodes during different time periods or frame cycles. By dynamically adjusting this electrical parameter, the system maintains operational simplicity while preventing noise accumulation that would otherwise degrade image quality.
3Speed
If touch sensing is performed during display active periods, then response time is reduced, but display noise interferes with touch detection accuracy
Solution Approach 1:
The patent schedules touch sensing operations to occur during specific periodic intervals within the display timing cycle, such as during horizontal blanking periods when electron beams are repositioning or during vertical retrace periods. These intervals are naturally occurring quiet periods in the display cycle when switching activity is minimal. By aligning touch sensing with these periodic windows, the system achieves the fastest possible response without suffering from display noise interference.
Solution Approach 2:
The patent uses display timing signals as feedback triggers to automatically determine when to initiate touch sensing operations. The timing signals provide real-time information about the display's operational state, and this feedback is used to synchronize touch sensing with optimal moments in the display cycle. This feedback mechanism ensures that touch sensing always occurs at the most favorable time without requiring complex manual scheduling, thereby maintaining both speed and accuracy.
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 touch sensing sensitivity while preventing image quality degradation by reducing the impact of display noise on the touch sensing array.
Implementation Method 1
a plurality of sensing electrodes forming second capacitance with the common electrode
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A touch controller includes a controller receiving a display timing signal and generating a touch sensing control signal synchronously with the display timing signal. The touch controller also includes a sensing circuit driving a touch sensing array in response to the touch sensing control signal in order to generate touch data corresponding to sensing signals provided by the touch sensing array. The sensing circuit provides a first driving signal having a first polarity to at least one driving channel of the touch sensing array during a first display frame period, and provides a second driving signal having a second polarity different from the first polarity during a second display frame period.