Common Electrode Touch Display Device Thickness Reduction
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Solution Overview
Problem
Existing capacitive touch screens are thick due to the need for two separate electrode layers for the Tx and Rx circuits.
Innovation Solution
A touch display device with a sub-pixel unit array and an array of common electrodes connected to a drive circuit through address lines, allowing the common electrodes to be connected to either a common voltage output or a touch signal processor depending on whether an image is being displayed or a touch signal is being scanned, thereby reducing thickness by enabling independent connection of each common electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two electrode layers are used for Tx and Rx circuits, then touch sensing function is achieved, but the touch screen becomes thick
Solution Approach 1:
The patent merges the Tx and Rx electrode functions into a single common electrode layer. The common electrode serves dual purposes: forming capacitance with pixel electrodes for display and acting as a sensing electrode for touch detection. This consolidation eliminates the need for separate Tx and Rx electrode layers, directly reducing touch screen thickness while maintaining touch sensing functionality.
Solution Approach 2:
The common electrode is designed to perform multiple functions simultaneously. It acts as both a display electrode (forming capacitance with pixel electrodes) and a touch sensing electrode (detecting touch signals through capacitive coupling). This multi-functionality allows the system to achieve touch sensing with a single electrode layer instead of requiring separate Tx and Rx layers.
2Ease of operation
If each common electrode is independently connected to drive circuit through address line, then touch signal scanning is enabled, but circuit complexity increases
Solution Approach 1:
The system dynamically switches the function of common electrodes between display mode and touch sensing mode through time-division multiplexing. During display periods, common electrodes function as display electrodes connected to voltage output. During touch sensing periods, they switch to sensing mode and are connected to the touch signal processor through address lines. This dynamic switching enables touch scanning capability while managing circuit complexity through temporal separation of functions.
Solution Approach 2:
The drive circuit operates in periodic cycles, alternating between display output mode and touch sensing mode. In each cycle, the common electrodes are sequentially connected to either the voltage output end (for display) or the touch signal processor (for sensing). This periodic switching enables the system to achieve both display and touch sensing functions using the same electrode structure without requiring permanently complex circuit connections.
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 design allows for thinner capacitive touch screens with improved touch performance, including higher resolution and resistance to environmental factors like mist or dew, by enabling simultaneous scanning of touch signals and image display without increasing thickness.
Implementation Method 1
When an image is displayed, the common electrodes each are connected to a common voltage output end in the drive circuit through the address line, forming an electric field between the common electrode and the pixel electrode
Implementation Method 2
When a touch signal is scanned, the common electrodes each are connected to a touch signal processor in the drive circuit through the address line, so as to receive the touch signal
Data Source
AI summary
Disclosed is a touch display device which belongs to the technical field of displays, and solves the technical problem that the existing capacitive touch screens are thick. The touch display device comprises an array of common electrodes and a plurality of address lines, each of the common electrodes being connected to a drive circuit through an address line respectively. When an image is displayed, the common electrode is connected to a common voltage output end through the address line, and when a touch signal is scanned, the common electrode is connected to a touch signal processor through the address line.