Touch Sensing Electrophoretic Display with Integrated Resistance Layer
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Solution Overview
Problem
Electrophoretic display devices with integrated touch sensing capabilities face issues with display quality deterioration due to the addition of touch panel components, which reduce reflected light and can cause substrate bending, leading to incorrect touch recognition and color separation problems.
Innovation Solution
A touch-sensitive electrophoretic display device is designed with a sensing layer made of materials like vanadium oxide, titanium, or silicon germanium, which changes electrical resistance in response to infrared or heat, integrated with a reflection-reducing metal oxide or nitride layer, a thin film transistor, and a color filter to maintain display quality even when bent, allowing for accurate touch sensing and image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If touch panel components are added to electrophoretic display, then touch sensing capability is improved, but display quality deteriorates due to reduced reflected light
Solution Approach 1:
The patent combines the touch sensing function and display function into a single integrated structure. The sensing layer is formed within the same device structure as the electrophoretic display, allowing touch detection and light reflection to coexist in the same optical path without requiring separate touch panel components that would block light.
Solution Approach 2:
The sensing layer serves multiple functions: it detects touch input through resistance changes while simultaneously allowing reflected light to pass through for display. This multi-functional design enables the same layer to contribute to both touch sensing capability and display quality maintenance.
2Adaptability or versatility
If substrate is made flexible for electrophoretic display, then adaptability is improved, but substrate bends from repeated touches causing incorrect touch recognition
Solution Approach 1:
The patent applies a rigid support layer to the flexible substrate before the electrophoretic display and sensing layers are fully assembled. This preliminary structural reinforcement prevents excessive bending during repeated touches, maintaining the geometric relationships between sensing elements and ensuring accurate touch position detection throughout the device lifecycle.
3Adaptability or versatility
If substrate bends from repeated touches, then flexibility is demonstrated, but color separation between pixels deteriorates
Solution Approach 1:
The rigid support layer is applied in advance to prevent substrate bending before pixel formation and color filter application. This preliminary reinforcement ensures that the precise geometric arrangement of sub-pixels and color filters remains stable during device assembly and operation, maintaining correct color separation even when the flexible display is bent during use.
4Measurement precision
If sensing layer materials with high infrared sensitivity are used, then touch sensing accuracy is improved, but light reflection is reduced
Solution Approach 1:
The sensing layer uses materials with specific local properties optimized for infrared detection (such as vanadium oxide or silicon germanium) while maintaining thin film structure that allows visible light transmission. The local material composition is tailored to be highly sensitive to infrared radiation from touch input while remaining transparent to the visible spectrum for display purposes.
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 correct touch sensing and image display without deteriorating the display quality, even when the device is bent, by using a sensing layer that responds to infrared or heat and a reflection-reducing layer to minimize light interference, ensuring accurate touch recognition and image fidelity.
Implementation Method 1
The sensing layer may be made of a material whose electrical resistance changes when exposed to changed levels of applied infrared (IR) rays or heat
Implementation Method 2
The sensing layer may be made of a material whose electrical resistance changes when exposed to changed levels of applied infrared (IR) rays or heat
Implementation Method 3
The electrophoretic layer may include microcapsules including electrophoretic particles. The electrophoretic particles may be divided into two types of electrophoretic particles having respective charges of opposed polarities
Data Source
AI summary
An image display device has touch sensing sensor components integrally distributed amongst pixel components of the device. In one embodiment, the distribution is one sensor component per one pixel component. In one embodiment, the pixel component forms a pixel portion of an image by selectively reflecting light and the sensor component is composed of a material that reflects light. More specifically, in one embodiment the light reflecting pixel component is an electrophoretic unit and the sensor component includes a layer of titanium having a color filter layer disposed below it and thus protectively covering it. Reflection of light from the light reflecting sensor layer is reduced by providing an anti-reflection layer above it. The sensor component changes resistance in response to change of local temperature or of an amount of infrared radiation impinging on it. Its resistance is measured by way of two wires connected thereto and extending through contact holes provided in the color filter layer.