In-Cell Touch Electrode Mode Switching for Liquid Crystal Protection
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Solution Overview
Problem
In-cell type liquid crystal display devices with built-in touch panels face issues with detecting touch events when the display is stopped, as applying DC voltage to the liquid crystal layer can cause damage.
Innovation Solution
The display device operates in two modes: one where the common electrode functions as both the display and scanning electrode, and another where a temporary scanning electrode is used, allowing for touch detection without applying voltage to the liquid crystal layer during display stop states, reducing power consumption and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the common electrode functions as both display and scanning electrode during display stop state, then power consumption is reduced, but the liquid crystal layer is damaged due to DC voltage application
Solution Approach 1:
The patent implements dynamic operation mode switching between first mode (display operation) and second mode (display stop state). In the second mode, the system dynamically selects either the common electrode or a temporary scanning electrode for touch detection, preventing DC voltage application to the liquid crystal layer while maintaining low power consumption. This dynamic adaptation resolves the contradiction between power savings and liquid crystal layer protection.
Solution Approach 2:
The patent introduces a temporary scanning electrode as an intermediary element that can be used instead of the common electrode during display stop state. This intermediary component enables touch detection functionality without requiring the common electrode to apply voltage to the liquid crystal layer, thus preventing damage while maintaining the ability to detect touches in low power mode.
2Reliability
If the common electrode is used for touch detection when display is stopped, then touch panel detection is enabled, but DC voltage is applied to the liquid crystal layer causing burning
Solution Approach 1:
The patent segments the electrode functions by separating the display function (common electrode) from the touch detection function (temporary scanning electrode). This segmentation allows the system to perform touch detection without involving the common electrode in voltage application to the liquid crystal layer, thereby preventing burning while maintaining reliable touch panel detection capability.
Solution Approach 2:
The temporary scanning electrode serves as an intermediary that enables touch detection functionality without requiring the common electrode to apply voltage to the liquid crystal layer. This intermediary component transfers the touch detection capability from the common electrode, preventing liquid crystal layer burning while maintaining detection reliability.
3Use of energy by stationary object
If display operation is stopped to reduce power consumption, then energy savings are achieved, but touch detection becomes problematic due to DC voltage application
Solution Approach 1:
The patent implements dynamic mode switching that adapts to different operational states. In display stop state, the system can dynamically select between using the common electrode or the temporary scanning electrode for touch detection based on the need to prevent DC voltage application. This dynamic behavior maintains both power savings and touch detection reliability.
Solution Approach 2:
The patent changes the operational parameters by switching between different electrode configurations. In display stop state, the system changes from using the common electrode for both display and touch detection to using the temporary scanning electrode for touch detection only. This parameter change enables the system to maintain low power consumption while ensuring reliable touch detection without liquid crystal layer damage.
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
Enables effective touch detection in both display and display stop states while minimizing power consumption and preventing liquid crystal layer damage.
Implementation Method 1
The touch panel of electrostatic capacitance type for detecting capacitance change at the touched point has been known
Implementation Method 2
the common electrode is allowed to function as an electrode for display and a scanning electrode for a touch panel, to which a common voltage and a first scanning pulse voltage are supplied
Data Source
AI summary
A display device is configured in a display state to allow the common electrode to function as an electrode for display and a scanning electrode for a touch panel, to which a common voltage and a first scanning pulse voltage are supplied, and to allow a detection circuit to detect a touched position based on the voltage detected by the first and the second detection electrodes. In a display stop state, the first detection electrode is configured to function as a temporary scanning electrode, and the detection circuit is configured to supply a second scanning pulse voltage to the first detection electrode so as to detect existence of a swipe based on the voltage detected by the second detection electrode.