Zigzag Color Filter Borders for LCD Surface Flatness
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Solution Overview
Problem
Liquid crystal display devices with color filters face challenges in maintaining a uniform surface flatness where color filter portions overlap, leading to non-uniform orientation films and liquid crystal layer thickness, especially when using negative photosensitive resins with steep film thickness gradients and imperfect mask positioning.
Innovation Solution
The manufacturing method involves using photomasks with unique patterns, such as zigzag or stepped borders, to control the film thickness of adjacent color filters, ensuring that the side portions of one color filter overlap with the other, creating inclined surfaces and wave patterns to maintain flatness even with negative photosensitive resins and imperfect mask alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a color filter is formed using negative photosensitive resin to cover and protect thin film transistors, then the transistors are protected from contact with liquid crystal, but the overlapping portions of adjacent color filters form protrusions that create surface non-uniformity
Solution Approach 1:
The patent applies preliminary action by forming a flattening film before the color filter is deposited. This flattening film is created in advance to compensate for the protrusions that will form during subsequent color filter deposition, ensuring that the final color filter surface remains uniform while maintaining transistor protection functionality
2Manufacturing precision
If the film thickness of color filter in overlapping portions is reduced to flatten the surface, then surface uniformity is improved, but it becomes extremely difficult to control the film thickness to half using negative photosensitive resin due to steep film thickness inclination
Solution Approach 1:
The patent introduces a flattening film as an intermediary layer between the substrate and the color filter. This mediator layer absorbs the complexity of thickness control by being formed with a specific thickness profile that compensates for future protrusions, allowing the color filter to be deposited with standard uniform thickness while achieving the desired flat surface
3Manufacturing precision
If additional flattening films are added to the structure to compensate for protrusions, then surface uniformity is achieved, but the device structure and manufacturing process become more complex
Solution Approach 1:
The patent merges the flattening function with the color filter structure by integrating the flattening film formation into the existing manufacturing process flow. The flattening film is combined with the color filter deposition sequence, allowing both functions (flattening and color filtering) to be achieved in a unified manufacturing approach rather than as separate additive steps
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 effectively flattens overlapping portions of color filters, ensuring a uniform surface and consistent liquid crystal layer thickness, even when masks are imperfectly positioned, without the need for additional flattening films.
Implementation Method 1
exposure to light and development are carried out in the region of the above described resin layer using a light exposure mask where a so-called halftone layer is formed
Data Source
AI summary
The present invention provides a manufacturing method for a liquid crystal display device, wherein the liquid crystal display device comprises first and second color filters provided on the liquid crystal side of one of a pair of substrates which are positioned so as to face each other and sandwich liquid crystal in between so as to be adjacent to each other, and a first side portion of the first color filter on the second color filter side overlaps with a second side portion of the second color filter on the first color filter side, characterized in that the border between the light blocking region and the non-light blocking region in a photomask for forming the first color filter, which corresponds to the first side portion, has a zigzag pattern with repeating mountains and valleys along this border, and the border between the light blocking region and the non-light blocking region in a photomask for forming the second color filter, which corresponds to the second side portion, has a zigzag pattern with repeating mountains and valleys along this border.