Display Device Water-Resistant Touch Detection
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Solution Overview
Problem
Touch detection in display devices with capacitance touch panels is hindered by water adherence, leading to inaccurate detection of object positions due to false capacitance changes.
Innovation Solution
The display device incorporates a substrate with pixel electrodes, first and second electrodes, gate and signal lines, switching elements, and a driver to supply drive signals, along with a controller to manage operations, enabling three detection modes (mutual capacitance, self-capacitance, and a guard electrode mode) to accurately detect touch inputs even with water on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitance touch detection is used in display devices, then touch detection function is enabled, but water adherence causes false capacitance changes leading to inaccurate detection
Solution Approach 1:
The touch detection function is divided into multiple detection modes (first detection mode using pixel electrodes, second detection mode using dedicated detection electrodes, third detection mode using gate lines and signal lines). This segmentation allows the system to switch between different detection methods depending on environmental conditions, particularly when water is present on the detection surface, thereby maintaining detection accuracy while preserving touch detection capability.
2Measurement precision
If guard signals are supplied to first electrodes synchronized with drive signals, then capacitance changes due to water adherence are suppressed, but device complexity increases
Solution Approach 1:
A driver circuit is introduced as an intermediary component that supplies guard signals to the first electrodes in synchronization with the drive signals. This intermediary component manages the complex timing and coordination required for the guard signal mechanism, isolating the complexity from the main control system while maintaining detection accuracy by suppressing false capacitance changes caused by water adherence.
3Measurement precision
If multiple detection modes are implemented, then accurate touch detection is achieved even with water present, but device complexity increases
Solution Approach 1:
The display device is designed with multi-functional electrodes that serve dual purposes: pixel electrodes function both as display elements and as detection electrodes for touch detection. Dedicated detection electrodes and gate lines also participate in detection across multiple modes. This universality allows the same hardware components to perform multiple functions, enabling accurate touch detection in various conditions without proportionally increasing device complexity.
Solution Approach 2:
The detection system dynamically switches between different detection modes (first detection mode, second detection mode, third detection mode) based on environmental conditions such as the presence of water on the detection surface. This dynamic adaptability allows the system to optimize detection accuracy for current conditions while using a unified hardware architecture, preventing static complexity from increasing proportionally with the number of detection modes.
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 allows for precise touch detection by distinguishing between water and actual object contacts, ensuring accurate positioning of detected objects even when water is present on the detection surface.
Implementation Method 1
capacitance is generated between common electrodes and sensor detection electrodes. The display device with a touch detection function described in JP-A-2009-244958 detects a change in the capacitance caused by a detected object
Data Source
AI summary
A display device includes a substrate, pixel electrodes, first electrodes, gate lines, signal lines, switching elements, a conductor, and a driver. The pixel electrodes are arrayed in a display region of the substrate. The first electrodes are separated from the pixel electrodes in a direction perpendicular to the substrate. The gate lines are disposed between the substrate and the first electrodes in the direction perpendicular to the substrate and extend in a plane parallel to the surface of the substrate. The signal lines intersect the gate lines in planar view. The switching elements are provided at the intersections of the gate lines and the signal lines. The conductor is provided opposite to the gate lines and the signal lines across the substrate in the direction perpendicular to the substrate.