Shield Electrode for Wearable Display Touch Accuracy
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Solution Overview
Problem
Wearable devices with touch detection functions, such as wristwatch-type devices, face challenges in achieving both high display quality and operability due to interference between touch detection capacitance and display-related capacitances, leading to detection errors and degraded display quality.
Innovation Solution
Incorporating a shield electrode or a predetermined space between the detection electrodes and the pixel or common electrodes, which shields the touch detection electric field from influences of display-related capacitances, thereby improving touch detection accuracy and maintaining display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor electrodes are arranged close to pixel electrodes to improve touch detection sensitivity, then touch detection accuracy improves, but display quality deteriorates due to capacitance interference
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the sensor electrode and the pixel electrode. This shield electrode acts as a mediator that blocks the electric field from the pixel electrode from interfering with the touch detection electric field, thereby allowing the sensor electrode to be positioned closer to the pixel electrode without compromising display quality.
Solution Approach 2:
The electrode structure is segmented into distinct functional zones: the sensor electrode for touch detection, the shield electrode for electromagnetic shielding, and the pixel electrode for display. This segmentation allows each component to perform its specific function independently, with the shield electrode creating an electromagnetic barrier that separates the touch detection function from the display function.
2Measurement precision
If shield electrode is added to block capacitance interference, then touch detection accuracy improves, but device complexity increases
Solution Approach 1:
The shield electrode serves multiple functions simultaneously: it acts as an electromagnetic shield to block interference from pixel electrodes, serves as a structural support element in the layered electrode configuration, and helps define the electric field boundaries for touch detection. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The shield electrode is integrated into the same substrate layer as the sensor electrode, and both are formed using similar fabrication processes. The shield electrode pattern is merged with the sensor electrode pattern in the circuit design, allowing both touch detection and electromagnetic shielding functions to be implemented in a unified electrode structure.
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 touch detection accuracy by isolating the touch detection electric field from display-related capacitances, reducing detection errors and maintaining high display quality in wearable devices.
Implementation Method 1
A shield electrode is arranged between a plurality of sensor electrodes and a pixel electrode or a common electrode which is located closest to a boundary between a display area and a non-display area surrounding the display area, in planar view
Implementation Method 2
wearable devices with a touch detection function
Data Source
AI summary
According to one embodiment, a display device includes a display area, a plurality of sensor electrodes and a shield electrode. The display panel includes a first substrate, a second substrate opposed to the first substrate, a liquid crystal layer sealed between the first substrate and the second substrate, a pixel electrode, and a counter-electrode. The plurality of sensor electrodes are arranged to surround the display area. The shield electrode is arranged between the plurality of sensor electrodes and the pixel electrode or the counter-electrode located closest to a boundary between the display area and a non-display area surrounding the display area, in planar view. A predetermined reference voltage is applied to the shield electrode.