Touch Panel Display Noise Reduction via Vertical Blanking Segmentation
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Solution Overview
Problem
In touch panel-equipped display devices, the overlap of sensing and potential switching periods during the vertical blanking period leads to noise induction in detection electrodes, reducing detection sensitivity, especially in on-cell and in-cell types where capacitive coupling is stronger.
Innovation Solution
The touch panel-equipped display device and its control method involve setting the sensing period and source bus line potential switching period to non-overlapping timings within the vertical blanking period, allowing for noise-free sensing by separating these operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing for touch panel and potential switching for source bus lines are conducted during the vertical blanking period, then noise from potential switching is reduced, but additional noise is generated due to capacitive coupling between source bus lines and detection electrodes
Solution Approach 1:
The vertical blanking period is divided into distinct time segments: a first period for touch panel sensing and a second period for source bus line potential switching. This temporal segmentation prevents overlap between the two operations, eliminating capacitive coupling noise while maintaining both functions.
Solution Approach 2:
The source bus line potential switching is performed after the touch panel sensing is completed within the vertical blanking period. This sequential arrangement ensures that the detection electrodes are not exposed to potential switching noise during the sensitive sensing period.
2Reliability
If source bus line potential switching is performed during the vertical blanking period, then display quality is maintained, but noise is induced in detection electrodes through capacitive coupling
Solution Approach 1:
The vertical blanking period is segmented into two non-overlapping intervals: one dedicated to touch sensing and another to source bus line potential switching. This segmentation allows both display quality maintenance and noise reduction to be achieved simultaneously.
Solution Approach 2:
Time acts as an intermediary parameter to separate the touch sensing operation from the source bus line potential switching operation. By introducing temporal separation, the harmful capacitive coupling effect is eliminated while preserving the beneficial functions of both operations.
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 enhances the detection sensitivity of touch panels by eliminating noise from potential switching, thereby improving the accuracy of touch detection without affecting display quality.
Implementation Method 1
source bus lines and detection electrodes of a touch panel are coupled via a constant capacitance 105. Therefore, if the sensing period for the touch panel and the potential switching period for the source bus lines overlap, electrical charges are induced in the detection electrodes through the capacitance 105
Data Source
AI summary
Provided is a touch panel-equipped display device (10) including: a touch panel (14); a display part (12) including source bus lines (25); a source bus line potential switching part that switches the potential of each source bus line (25) in a source bus line potential switching period (54) that is a partial period of a vertical blanking period (51); and a sensing part that performs sensing for a touch panel in a sensing period (53) that is a period in the vertical blanking period (51) other than the partial period.