Common Electrode Integration in Capacitive Touch Displays
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Solution Overview
Problem
Existing capacitive touch screens are thick due to the need for two electrode layers, one for the Tx circuit and the other for the Rx circuit.
Innovation Solution
A touch display device with a sub-pixel unit array, thin film transistor, and pixel electrode, where a common electrode is connected to a drive circuit through an address line, allowing for independent connection and reducing thickness by enabling touch signal sensing solely through the array of common electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two electrode layers (Tx and Rx) are used for capacitive touch sensing, then touch signal detection capability is improved, but the overall thickness of the touch screen increases
Solution Approach 1:
The patent combines the Tx and Rx electrode functions into a single common electrode layer. This common electrode serves dual purposes: forming capacitive coupling with pixel electrodes for display and detecting touch signals through capacitance changes. By merging the two separate electrode layers into one, the touch screen thickness is reduced while maintaining touch detection functionality.
Solution Approach 2:
The common electrode performs multiple functions simultaneously: it acts as both the transmit electrode (Tx) and receive electrode (Rx) for touch sensing, and also forms part of the display structure by creating electric fields with pixel electrodes. This multi-functional design eliminates the need for separate electrode layers, thereby reducing overall thickness.
2Adaptability or versatility
If separate electrode layers are used for display and touch functions, then functional independence is improved, but structural complexity and thickness increase
Solution Approach 1:
The patent merges the display electrode and touch sensing electrode into a single common electrode structure. This common electrode is positioned between the pixel electrode and the touch sensing layer, creating a integrated structure that serves both display and touch functions without requiring separate electrode layers.
Solution Approach 2:
The patent introduces a new spatial arrangement by placing the common electrode in an intermediate position between the pixel electrode and the touch sensing layer. This dimensional reorganization allows the same electrode structure to participate in both display electric field formation and touch signal detection, reducing structural complexity while maintaining functional independence.
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
The solution decreases the thickness of capacitive touch screens, improves touch performance, and enhances display resolution by allowing separate scanning of image and touch signals, while maintaining effective touch reporting even in adverse conditions.
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: a sub-pixel unit array, each of the sub-pixel unit being provided a thin film transistor and a pixel electrode therein, with a first insulating layer and a second insulating layer provided between the thin film transistor and the pixel electrode; and an array of common electrodes and a plurality of address lines located between the first insulating layer and the second insulating layer, each of the common electrodes being connected to a drive circuit through an address line respectively.