In-Cell Touch Display Conducting Layer Segmentation
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Solution Overview
Problem
In-cell touch displays lack sensitivity due to similar capacitance readings before and after touch, making it difficult to accurately determine touch positions.
Innovation Solution
The touch display incorporates a substrate with pixels, first and second conducting layers, and third conducting layers to generate and sense touch signals, with the data driver outputting touch driving signals during blanking periods to enhance sensitivity by varying capacitance between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an in-cell touch display uses conventional transmitting and receiving terminal conducting layers, then the display can reduce thickness and eliminate additional touch panels, but the capacitance difference before and after touch is very small resulting in poor touch sensitivity
Solution Approach 1:
The conducting layers are segmented into multiple functional layers: first conducting layer (receiving terminal), second conducting layer (transmitting terminal), and third conducting layer (sensing terminal). This segmentation allows each layer to perform specific functions, with the third layer dedicated to sensing touch capacitance changes, thereby improving measurement precision without increasing overall device complexity.
Solution Approach 2:
The patent introduces a third conducting layer in the vertical stacking dimension, transitioning from a conventional two-layer structure to a three-layer structure. This dimensional addition enables independent optimization of transmitting and sensing functions, allowing the sensing layer to specifically detect touch-induced capacitance changes while the other layers handle signal transmission.
2Device complexity
If the capacitance between conducting layers remains similar before and after touch, then the display maintains structural simplicity, but the touch sensing signal difference is negligible making accurate touch position detection difficult
Solution Approach 1:
The third conducting layer acts as an intermediary sensing element between the user's touch and the signal processing circuitry. This intermediary layer is specifically positioned and configured to detect capacitance changes caused by touch, converting the physical touch event into a measurable electrical signal without requiring changes to the user's interaction method.
Solution Approach 2:
The data line serves multiple functions: it transmits image data to pixel electrodes during normal display operation and transmits touch driving signals to the first conducting layer during touch sensing operation. This multi-functionality allows the system to maintain structural simplicity while enabling sophisticated touch detection capabilities through temporal multiplexing of the same physical infrastructure.
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 significantly improves sensitivity by creating a noticeable difference in touch sensing signals, allowing for more accurate detection of touch positions on the display.
Implementation Method 1
After receiving a touch driving signal DS, the transmitting terminal conducting layer 102 generates an electromagnetic signal Tx
Implementation Method 2
the capacitance C4 between the two conducting layers 102, 104 will change, thus the receiving terminal conducting layer 104 will generate a touch sensing signal TS
Implementation Method 3
The second conducting layer is formed at a side of the first conducting layer, insulated from the first conducting layer, and configured to generate an electrical field with the pixel electrode so as to drive a liquid crystal layer
Data Source
AI summary
A touch display includes a plurality of pixels, a plurality of scan lines, a plurality of data lines, a plurality of first conducting layers, and a plurality of third conducting layers. The plurality of scan lines are coupled to the plurality of pixels. The plurality of data lines are coupled to the plurality of pixels and the plurality of first conducting layers to provide a touch driving signal. Each first conducting layer of the plurality of first conducting layers is configured to receive the touch driving signal. The plurality of third conducting layers is configured to output a touch sensing signal according to the touch driving signals outputted by the plurality of first conducting layers.