Color Filter Substrate Ring Protrusions for Polyimide Backflow Control
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Solution Overview
Problem
In the fabrication of LTPS display panels, the polyimide film tends to flow back and accumulate around photo spacers, causing a 'halo effect' that leads to uneven liquid crystal molecule orientation and requires a black matrix to block light, which increases the size of the black matrix and reduces display panel performance.
Innovation Solution
A color filter substrate with a black matrix featuring first and second ring protrusions on its edge and periphery, respectively, is used to prevent polyimide solution backflow, with a fabricating method involving a half-tone mask exposure and etching process to form these protrusions, allowing the polyimide film to coat evenly and reducing the halo effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a black matrix is disposed below the halo area to block light, then the liquid crystal molecule orientation in halo area is improved, but the size of the black matrix increases and the open ratio of the display panel decreases
Solution Approach 1:
The patent applies preliminary action by forming the first ring protrusion on the black matrix edge before coating the polyimide film. This protrusion structure is pre-established to prevent polyimide solution backflow during the coating process, thereby preventing halo effect formation and eliminating the need for an enlarged black matrix to block light in halo areas.
Solution Approach 2:
The patent extracts the harmful polyimide solution backflow from the system by introducing the first ring protrusion that acts as a physical barrier. This protrusion prevents the polyimide solution from flowing back to the periphery and accumulating in halo areas, effectively removing the source of the problem rather than addressing its consequences.
2Ease of manufacture
If the polyimide film is coated on the planar layer, then the alignment film is formed, but the polyimide solution flows back from the periphery of the photo spacer to cause halo effect
Solution Approach 1:
The first ring protrusion serves as an intermediary structure between the black matrix and the polyimide film. It acts as a physical barrier that mediates the interaction between the polyimide solution and the periphery of the photo spacer, preventing the solution from flowing back and accumulating while still allowing the coating process to proceed normally.
Solution Approach 2:
The patent segments the black matrix structure by adding the first ring protrusion as a distinct feature. This segmentation creates a localized barrier zone that specifically addresses the polyimide solution backflow problem at the critical interface between the black matrix and photo spacer periphery, without affecting the overall coating process.
3Manufacturing precision
If the photo spacer protrudes on the color filter substrate, then the cell gap is controlled, but the polyimide solution accumulates around the photo spacer to cause halo effect
Solution Approach 1:
The first ring protrusion acts as an intermediary barrier between the photo spacer periphery and the polyimide solution. It prevents the solution from accumulating around the protruding photo spacer while maintaining the cell gap control function, effectively decoupling the two issues.
Solution Approach 2:
The patent applies preliminary anti-action by pre-forming the first ring protrusion before coating the polyimide film. This protrusion is designed specifically to counteract the harmful effect of polyimide solution backflow, creating a preventive barrier that stops the accumulation problem before it can occur.
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 design reduces the halo area of the polyimide film, increases the open ratio of the display panel, and enhances the display performance by minimizing the size of the black matrix and improving liquid crystal molecule alignment.
Implementation Method 1
applying a half-tone mask with three transmittance to perform an exposing procedure on the glass substrate with the photoresist layer
Implementation Method 2
etching the glass substrate after the exposing procedure to form a pattern of the black matrix and the at least one first ring protrusion
Data Source
AI summary
A color filter substrate and the fabricating method are provided. The color filter substrate comprises of the following elements. A glass substrate and a black matrix formed thereon. The black matrix includes a first ring protrusion on an edge thereof. Color resists, a planar layer and a photoresist spacer are disposed in sequence on the glass substrate. The planar layer includes a second ring protrusion formed thereon corresponding to a location of the first ring protrusion. A projection of the photoresist spacer on the glass substrate is inside the first ring protrusion and the second ring protrusion. A polyimide film is coated on the planar layer and the photoresist spacer. The second ring protrusions can block the backflow of the polyimide solution on the photoresist spacer, for reducing the halo area of polyimide film, increasing the open ratio of the panel and promoting the performance of the LTPS display.