COT Substrate Stripe Color Filters Eliminate Black Matrix
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices with a color filter-on-thin film transistor (COT) substrate face issues of light leakage and deteriorated aperture ratio due to the use of a black matrix film, which increases manufacturing costs and decreases productivity.
Innovation Solution
The COT substrate incorporates stripe-shaped color filters that overlap pixel electrodes and are parallel to gate or data lines, eliminating the need for a black matrix film by absorbing external light, thereby reducing reflections and preventing TFT malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix film is used to prevent light leakage and reflect external light, then light leakage is reduced and external light reflection is minimized, but the aperture ratio deteriorates and manufacturing complexity increases
Solution Approach 1:
The patent removes the black matrix film from the LCD structure entirely. Instead of using a separate black matrix layer to block light, the invention uses the color filter layer itself to absorb external light and prevent light leakage, thereby eliminating the need for the black matrix film and preserving the aperture ratio.
Solution Approach 2:
The color filter layer is given multiple functions: it not only provides color filtration for the liquid crystal cells but also simultaneously acts as a light-blocking layer to prevent external light from reaching the TFTs and causing malfunctions. This multi-functionality eliminates the need for a separate black matrix film.
2Reliability
If a black matrix film is used to reflect external light and prevent TFT malfunction, then external light reflection is reduced and TFT reliability is improved, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent combines the light-blocking function previously performed by a separate black matrix film with the color filter layer. By merging these two functions into a single layer, the manufacturing process is simplified, fewer steps are required, and productivity is improved while maintaining TFT reliability.
3Object-affected harmful factors
If the width of the black matrix film is increased to minimize light-leakage defect, then light leakage is reduced, but the aperture ratio deteriorates
Solution Approach 1:
The invention extracts and removes the black matrix film from the structure, eliminating the need to choose its width. Instead, the color filter layer is designed to extend to the edges of the pixel electrodes, naturally defining the aperture boundaries without requiring a separate black matrix layer whose width would compromise the aperture ratio.
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 reduces manufacturing costs and increases productivity by eliminating the need for additional mask processes, while effectively absorbing external light and preventing light leakage, thus enhancing the aperture ratio and preventing TFT malfunctions.
Implementation Method 1
The COT substrate incorporates stripe-shaped color filters that overlap pixel electrodes and are parallel to gate or data lines, eliminating the need for a black matrix film by absorbing external light, thereby reducing reflections and preventing TFT malfunction.
Data Source
AI summary
A color filter-on-thin film transistor substrate includes gate data lines crossing each other and defining pixel areas, thin film transistors is located at crossings of gate and data lines, pixel electrodes connected to the thin film transistors and formed within the pixel areas, and stripe-shaped color filters overlapping a plurality of pixel areas and oriented parallel to one of the gate and data lines.