Touch Insulating Layer Stack for Low-Reflectance Display Panels
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Solution Overview
Problem
Display devices with integrated touch sensing units experience reflectance distortion due to differences in refractive indexes of color filters, leading to reduced display quality and user satisfaction.
Innovation Solution
Enhance the refractive indexes of touch insulating layers by adjusting their thickness and material composition to achieve destructive interference of reflected light, thereby reducing light reflectance and minimizing refractive index disparities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the touch sensing unit is formed integrally with the image display area, then the device thickness is reduced, but light reflectance increases due to refractive index differences
Solution Approach 1:
The patent modifies the refractive index parameter of the touch insulating layers by selecting specific materials (such as SiOx with refractive index 1.45-1.65) and adjusting their thickness (50-200 nm) to optimize optical properties. This parameter change reduces light reflectance while maintaining the integrated structure's thinness.
Solution Approach 2:
The patent employs composite material structures by combining multiple touch insulating layers with different refractive indices (first layer: 1.60-1.70, second layer: 1.45-1.65) to create an optical gradient that minimizes reflectance. This composite approach allows the integrated display to maintain thinness while reducing the harmful reflectance effect.
2Object-generated harmful factors
If the refractive index of touch insulating layers is increased to reduce reflectance, then light reflectance decreases, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by assigning different refractive index requirements to different regions of the touch insulating layers. The first touch insulating layer has a higher refractive index (1.60-1.70) while the second layer has a lower refractive index (1.45-1.65), creating a gradient that reduces reflectance. This localized differentiation is achieved through standard semiconductor manufacturing processes.
Solution Approach 2:
The patent introduces an intermediary approach by using the second touch insulating layer with intermediate refractive index (1.45-1.65) between the first layer (1.60-1.70) and the color filter layer. This intermediary layer acts as a transition zone that gradually changes the refractive index, reducing reflectance without requiring extreme material properties that would complicate manufacturing.
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
Prevents reflectance distortion and improves display quality by lowering light reflectance, enhancing user satisfaction and reliability.
Implementation Method 1
lowering the light reflectance of touch insulating layers by enhancing the refractive indexes of the touch insulating layers to increase destructive interference of lights reflected by the touch insulating layers
Data Source
AI summary
A display device comprises a display panel including a display area having pixels, and a touch sensing unit disposed on a front surface of the display panel and sensing a user's touch. The touch sensing unit comprises a first touch insulating layer on an encapsulation layer in the display area, a second touch insulating layer on the first touch insulating layer, touch electrodes on the second touch insulating layer, a third touch insulating layer on the touch electrodes and the second touch insulating layer, a color filter layer on the third touch insulating layer and overlapping with the pixels, and at least one cover window on the color filter layer and the display panel. The third touch insulating layer is composed of an insulating material having a refractive index ranging between a refractive index of the second touch insulating layer and a refractive index of the color filter layer.