Integrated Display Common Electrode Interconnect Architecture
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Solution Overview
Problem
Capacitive sense arrays in touch screens typically require dedicated touch sensing layers separate from display layers, which can compromise display quality and refresh rate when integrated, and there is a need to enhance interconnect resistance for both display and touch sensing elements.
Innovation Solution
An integrated display device with a two-dimensional array of display elements and capacitive sense elements sharing common electrodes, where interconnects are arranged to reduce parasitic resistance, allowing for efficient transition between display driving and touch sensing modes without impacting display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sense arrays use dedicated touch sensing layers separate from display layers, then touch sensing functionality is achieved, but display quality and refresh rate are compromised
Solution Approach 1:
The patent merges the touch sensing function and display function into a single integrated layer structure. The common electrode layer serves dual purposes: as part of the display pixel structure and as the capacitive sensing electrode. This eliminates the need for separate dedicated touch sensing layers while maintaining both display quality and touch sensing functionality.
Solution Approach 2:
The common electrode layer is designed to perform multiple functions simultaneously. It acts as both the common electrode for liquid crystal display operation and the sensing electrode for capacitive touch detection. This multi-functionality resolves the contradiction by eliminating the need for separate layers while preserving both display and touch sensing performance.
2Device complexity
If integrated display and touch sensing share common electrodes, then manufacturing complexity is reduced, but interconnect resistance increases
Solution Approach 1:
The patent segments the interconnect system into dedicated display control interconnects and dedicated sensing control interconnects that operate independently. Display control interconnects drive the display electrodes while sensing control interconnects read the capacitive sensing signals from common electrodes. This segmentation prevents signal interference and maintains low effective resistance for both functions despite sharing the common electrode layer.
Solution Approach 2:
The patent introduces separate control interconnects as intermediaries between the control circuitry and the shared common electrodes. Display control interconnects provide driving signals to display electrodes, while sensing control interconnects provide reference voltages and read sensing signals from common electrodes. These intermediary interconnects isolate the two functions electrically, preventing resistance issues from affecting both functions simultaneously.
3Speed
If transition between display driving mode and touch sensing mode is rapid, then user interface responsiveness is improved, but display quality may be impacted
Solution Approach 1:
The patent implements periodic switching between display driving mode and touch sensing mode through time-division multiplexing. The system alternates between periods of display operation and periods of touch sensing operation in a regular cycle. This periodic action allows rapid mode transitions while maintaining display quality, as each mode operates during its designated time window without interference from the other mode.
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 enables seamless integration of touch detection into display infrastructure without compromising display quality or refresh rate, improving both display performance and touch sensing accuracy by reducing interconnect resistance and enhancing transition rates between modes.
Implementation Method 1
Capacitances of these capacitive sense elements vary when an object (e.g., a finger, a hand, a stylus, or another object) comes into contact with or hovers above the touch sensing surface
Data Source
AI summary
This application is directed to a display device that integrates a two-dimensional array of display elements and a two-dimensional array of capacitive sense elements. A common electrode layer includes a two-dimensional array of common electrodes, which are used in both display elements and capacitive sense elements. One or more sensing control interconnects and a plurality of driving interconnects are arranged in parallel with each other and on top of a first row of common electrodes. Each sensing control interconnect is configured to provide a touch sensing control signal to enable/disable electrical access to common electrodes in the first row of common electrodes in a touch sensing mode. Each common electrode in the first row is electrically coupled to two or more respective driving interconnects in a display driving mode, while each of the plurality of driving interconnects is electrically coupled to a single respective common electrode.