Floating Electrode Touch Sensing for Display Apparatuses
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Solution Overview
Problem
Conventional touch-sensitive display apparatuses face challenges in accurately determining touch coordinates due to variations in capacitance caused by the width of insulating substrates, black matrices, and color filters, which affect the sensitivity and reliability of touch sensing.
Innovation Solution
The introduction of a floating electrode in the non-display region, which forms capacitors with the touch lines, allows for a more significant capacitance change upon touch, enhancing touch sensing sensitivity by forming user capacitors between the floating electrode and ground, thereby improving the detection of touch coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width of insulating substrate, black matrix, color filter increases, then the capacitance of inner capacitor increases, but the capacitance of outer capacitor decreases
Solution Approach 1:
A floating electrode is introduced as an intermediary element between the touch lines and the external environment. This floating electrode forms a user capacitor with the touch lines when a user touches the display, serving as a mediator to enhance the capacitive coupling effect and improve touch sensing sensitivity without requiring changes to the underlying insulating substrate, black matrix, or color filter structures.
Solution Approach 2:
The solution moves the capacitance enhancement mechanism from the vertical dimension (changing widths of insulating substrate, black matrix, color filter) to the horizontal dimension by introducing a floating electrode that spans across multiple touch lines. This dimensional shift allows for enhanced capacitive coupling without increasing the complexity of the vertical stack structure.
2Measurement precision
If only one touch line is disposed in non-display region, then the device structure is simplified, but touch coordinate determination accuracy is reduced
Solution Approach 1:
The floating electrode merges the functionality of multiple touch line segments by providing a continuous conductive path that couples with multiple underlying touch lines simultaneously. This merging effect enhances the capacitive signal for touch coordinate determination without requiring multiple separate touch line configurations in the non-display region.
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 design significantly enhances touch sensing sensitivity by ensuring that the capacitance changes are more pronounced and easily detectable, leading to improved accuracy in determining touch positions on the display apparatus.
Implementation Method 1
a first common capacitor Cr is formed between the first touch line Rx1 and the common electrode, which is applied with the common voltage Vcom. a second common capacitor Ct is formed between the second touch line Tx1 and the common electrode, which is applied with the common voltage Vcom
Data Source
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AI summary
A display apparatus includes a first substrate, a second substrate overlapping the first substrate, an image display part disposed between the first substrate and the second substrate, and a black matrix disposed on the second substrate. The display apparatus further includes a floating electrode overlapping the black matrix and being electrically floating. The display apparatus further includes first-type touch lines extending in a first direction, arranged along a second direction, electrically insulated from each other, and including a primary first-type touch line. The primary first-type touch line overlaps and is insulated from the floating electrode. The display apparatus further includes second-type touch lines extending in the second direction, arranged along the first direction, electrically insulated from each other, and including a primary second-type touch line. The primary second-type touch line overlaps and is insulated from the floating electrode.