Capacitive Touch Sensor Integrated with LCD Display
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Solution Overview
Problem
Traditional capacitive touch sensors require two layers of transparent conductive traces, which complicates their integration with LCD displays and increases manufacturing complexity, whereas existing solutions for multi-touch functionality often require additional layers or separate touch panels, leading to higher costs and potential noise interference.
Innovation Solution
A capacitive touch sensor with a single layer of transparent sensor traces integrated above an LCD display panel, where the LCD's gate or source signal lines are used to emit excitation signals in a time-division manner, simplifying the structure and eliminating the need for dedicated touch sensor traces, and allowing synchronization with display functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two layers of transparent conductive traces are used for capacitive touch sensor, then touch sensing functionality is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the touch sensor excitation signal lines with the LCD display signal lines. The display's gate or source lines are used to emit excitation signals for the touch sensor, eliminating the need for separate dedicated touch sensor trace layers. This integration reduces structural complexity while maintaining touch sensing functionality.
Solution Approach 2:
The display signal lines serve dual purposes: they drive the display pixels and simultaneously function as excitation lines for the capacitive touch sensor. This multi-functionality reduces the overall component count and simplifies the device structure.
2Adaptability or versatility
If additional layers are added for multi-touch functionality, then touch sensing capability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent combines the touch sensor circuitry with the display circuitry by using the same signal lines for both display driving and touch excitation. This eliminates the need for separate additional layers and reduces manufacturing steps, lowering production costs while achieving multi-touch capability.
Solution Approach 2:
The signal lines are designed to perform multiple functions - driving display pixels during one time period and providing excitation signals for touch sensing during another time period. This multi-functionality avoids the need for separate dedicated touch layers, reducing manufacturing complexity.
3Reliability
If separate touch panels are used, then touch sensing is achieved, but noise interference from display functionality affects touch performance
Solution Approach 1:
The patent uses time-division multiplexing where the signal lines are alternately used for display driving and touch excitation in periodic time slots. This temporal separation prevents simultaneous operation that would cause noise interference, allowing the touch sensor to operate without display-related electrical noise.
Solution Approach 2:
The system dynamically switches the function of signal lines between display driving mode and touch excitation mode based on time requirements. This dynamic reconfiguration allows the same hardware to serve both purposes without creating permanent noise pathways that would interfere with touch sensing accuracy.
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 approach simplifies the manufacturing of capacitive touch sensors, reduces costs by sharing circuitry with the display, and minimizes noise interference by integrating touch sensing directly into the display panel without additional layers, enhancing the efficiency and effectiveness of touch functionality.
Implementation Method 1
capacitive touch sensor
Implementation Method 2
transparent conductive traces
Data Source
AI summary
A capacitive touch sensor (touch sensitive panel or screen) partially integrate with an LCD is disclosed. The touch sensor includes an LCD panel and a single layer of transparent conductive traces above the LCD panel. One group of signal traces of the LCD panel, either the gate signal traces or the source signal traces, is used to emit signals that function as the excitation signals of the touch sensor, and the single layer of transparent conductive traces is used to detect the signals to sense touches. The single layer of transparent conductive traces may be form on a flexible medium and affixed to the upper surface of the LCD panel. The LCD panel may be similar to a conventional LCD panel except that the driver circuit is modified so that the gate or source signals are used, in a time-division manner, as excitation signals of the touch sensor.