Capacitive Touch Screen Electrode Integration on LCD Color Filter Substrate
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Solution Overview
Problem
Liquid crystal display devices with touch screens experience a reduction in light transmittance and increased costs due to the addition of a separate touch screen substrate.
Innovation Solution
The implementation of a capacitive touch screen system where the transparent conductive layer on the color filter substrate serves as both the touch screen electrode, eliminating the need for a separate touch screen substrate and maintaining light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate touch screen substrate is attached to the front side of the liquid crystal display panel, then touch screen function is achieved, but light transmittance is reduced by approximately 15%
Solution Approach 1:
The patent merges the touch screen electrode function with the existing transparent conductive layer on the color filter substrate. Instead of adding a separate touch screen substrate, the transparent conductive layer is configured to serve dual purposes: as the transparent electrode for the liquid crystal display and as the touch sensor electrode for capacitive touch detection. This integration eliminates the need for additional layers that would block light while maintaining both display and touch functionality.
Solution Approach 2:
The transparent conductive layer is designed to perform multiple functions simultaneously. It serves as the transparent electrode for the liquid crystal display panel and as the touch sensor electrode for capacitive touch detection. This multi-functional design allows the same structural element to provide both optical transparency for display and electrical functionality for touch sensing, thereby avoiding the light transmittance reduction that would occur with a separate touch screen substrate.
2Adaptability or versatility
If a separate touch screen substrate is attached to the front side of the liquid crystal display panel, then touch screen function is achieved, but cost increases due to extra parts
Solution Approach 1:
The patent combines the touch screen functionality into the existing liquid crystal display panel structure by utilizing the transparent conductive layer already present on the color filter substrate. This merging approach eliminates the need for a separate touch screen substrate and its associated manufacturing, assembly, and material costs, thereby achieving cost reduction while maintaining touch screen function.
Solution Approach 2:
The transparent conductive layer is designed to serve dual purposes: as the transparent electrode for the liquid crystal display and as the touch sensor electrode for capacitive touch detection. This multi-functional design eliminates the need for additional components and reduces manufacturing complexity, leading to cost savings while achieving both display and touch functionality in a single integrated structure.
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 solution prevents the reduction in light transmittance and decreases costs by utilizing the existing transparent conductive layer as the touch screen electrode, resulting in a more efficient and cost-effective liquid crystal display device with a capacitive high-transmittance touch screen.
Implementation Method 1
A capacitive touch screen is known as one of the touch screen technologies. A typical capacitive touch screen includes a touch screen substrate in which a conductive coating (transparent conductive layer) is applied on the front side (and the backside) of a glass substrate, and position detection is carried out when a finger of an operator touches the touch screen substrate.
Implementation Method 2
In an IPS liquid crystal display device, pixel electrodes and counter electrodes are formed on the same substrate and an electric field is applied between each pair of the pixel electrodes and the counter electrodes to rotate liquid crystal molecules in the substrate plane for contrast control.
Data Source
AI summary
A liquid crystal display device includes a first substrate, a second substrate, and a liquid crystal material sandwiched between the first and second substrate. The second substrate has a touch screen electrode directly on a front-side surface of the second substrate. The first substrate has a wiring line for supplying a position detection voltage. A conductive tape electrically connects between the touch screen electrode and a driver circuit. A polarization plate is disposed above the touch screen electrode.