In-Cell Touch Display Counter Electrode Segmentation for Ghost Detection
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Solution Overview
Problem
In-cell type liquid crystal display devices with built-in touch panels often experience erroneous capacitance detection due to foreign matter like noise and water droplets, leading to touch detection errors, commonly referred to as 'imaginary touch' or 'ghost' detections.
Innovation Solution
The solution involves dividing the counter electrode into multiple blocks, which serve as scanning electrodes for the touch panel, and using a detection circuit to differentiate between noise and water droplets by analyzing the current flowing through detection electrodes, assuming the presence of an additional counter electrode, and applying touch panel scanning voltage in synchronization with the existing blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the counter electrode is used as a single block for touch panel scanning, then the device structure is simple, but noise and water droplets cause erroneous capacitance detection leading to imaginary touch
Solution Approach 1:
The counter electrode is divided into multiple blocks (first counter electrode block and second counter electrode block) instead of using a single block. This segmentation allows independent control and scanning of each block, enabling the detection circuit to distinguish between actual touches and false signals from noise or water droplets by comparing capacitance changes across different blocks, thereby improving touch detection accuracy.
2Reliability
If the counter electrode is divided into multiple blocks for sequential scanning, then imaginary touch detection is reduced, but the scanning time and complexity increase
Solution Approach 1:
The touch panel scanning is performed periodically by sequentially switching between the first and second counter electrode blocks. The drive circuit alternates the scanning operation between these blocks in a periodic manner, which reduces imaginary touch detection while maintaining efficient scanning speed through regular alternation rather than continuous complex scanning of a single large electrode.
Solution Approach 2:
By dividing the counter electrode into multiple smaller blocks that can be scanned independently and sequentially, the total scanning time is distributed across blocks. This segmentation allows for faster individual block scanning compared to scanning one large electrode, thereby reducing overall scanning time while improving detection accuracy.
3Reliability
If the detection circuit analyzes current from multiple counter electrode blocks, then noise and water droplet interference is distinguished, but the detection circuit complexity increases
Solution Approach 1:
The detection circuit is designed to process signals from multiple segmented counter electrode blocks separately. By analyzing capacitance changes from each block independently and comparing them, the circuit can distinguish between actual touches (which affect specific localized areas) and noise or water droplets (which may affect multiple blocks differently). This segmented approach improves differentiation capability while keeping the detection logic relatively simple.
Solution Approach 2:
The detection circuit uses feedback from the capacitance measurements of multiple counter electrode blocks to determine whether a touch has occurred. By continuously monitoring and comparing the capacitance values from different blocks, the circuit can identify patterns characteristic of actual touches versus noise or water droplets, improving reliability through comparative feedback analysis.
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 effectively reduces the influence of imaginary touch 'ghost' on touch detection, allowing for accurate identification and differentiation between noise and water droplet interference, thereby improving the reliability of touch detection in liquid crystal display devices.
Implementation Method 1
The touch panel of electrostatic capacitance type has been known as the one for detecting the capacitance change in the touched part
Implementation Method 2
The touch panel of electrostatic capacitance type has been known as the one for detecting the capacitance change in the touched part
Data Source
AI summary
A display device is configured to (a) detect presence or absence of noise or water droplet adhesion based on current flowing through a plurality of detection electrodes upon supply of a touch panel scanning voltage to m divided blocks of the counter electrode, and (b) distinguish between noise and water droplet based on the current flowing through the detection electrodes on the assumption that a (m+1)th counter electrodes exists in addition to the m divided blocks of the counter electrode, and the touch panel scanning voltage is supplied to the (m+1)th counter electrode, which is in synchronization with the touch panel scanning voltage supplied to the m divided blocks of the counter electrode.