Color Filter Isolation Layer for Inkjet Printing Spill Control
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Solution Overview
Problem
Inkjet printing of color filters for liquid crystal displays faces issues with color pigment spilling and uneven surfaces due to high solvent vaporization and surface tension, leading to color mixing and insufficient saturation, as well as challenges in achieving uniform thickness and even surfaces.
Innovation Solution
A manufacturing method involving the formation of an isolation layer on the black matrix using photosensitive materials, followed by lithography and thermal treatment, which allows for precise filling and drying of color pigments, and subsequent patterning of photo spacers to maintain uniform film thickness and prevent color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the color pigment is filled using inkjet printing with high solvent content, then the color saturation is improved, but the color pigment spills out of the pixel areas causing color mixing
Solution Approach 1:
A hydrophobic layer is formed on the black matrix before filling the color pigment. This preliminary action creates a barrier that prevents the color pigment from spreading beyond the pixel areas, allowing sufficient pigment to be filled for saturation while maintaining boundary precision.
Solution Approach 2:
The hydrophobic layer acts as an intermediary between the black matrix and the color pigment. It modifies the surface properties to control pigment placement, enabling the pigment to remain confined within pixel areas while still achieving adequate saturation.
2Quantity of substance
If the color pigment column is made larger to ensure full pixel area filling, then the pixel areas are fully filled, but the color pigment spills out causing color mixing
Solution Approach 1:
The hydrophobic layer is prepared in advance on the black matrix surface. This allows the color pigment to be deposited with sufficient volume for complete pixel area filling without worrying about spillage, as the hydrophobic layer will contain it within the pixel boundaries.
Solution Approach 2:
The potential harmful effect of high flow velocity causing spillage is converted into a benefit by using the hydrophobic layer to deliberately control and direct the pigment flow. The pigment is allowed to flow freely within the pixel area, and the hydrophobic layer ensures it stops exactly at the boundaries.
3Manufacturing precision
If a hydrophobic treatment is performed on the black matrix to modify surface tension, then the color pigment placement is improved, but an uneven surface with center protuberance is created
Solution Approach 1:
The patent introduces an additional hydrophobic layer above the black matrix's hydrophobic treatment. This intermediate layer serves as a new interface that prevents the center protuberance formation while maintaining the placement precision benefits of the underlying hydrophobic treatment.
Solution Approach 2:
The patent modifies the surface tension parameters by adding another hydrophobic layer. This changes the overall surface properties to achieve a balance between placement precision and surface uniformity, eliminating the center protuberance while retaining the confinement effect.
4Object-generated harmful factors
If the black matrix film thickness is increased to prevent color pigment spilling, then color mixing is prevented, but the follow-up film layer coverage becomes difficult
Solution Approach 1:
Instead of increasing the black matrix thickness, the patent applies a hydrophobic layer in advance. This preliminary measure provides the spill prevention function without adding to the matrix thickness, thereby maintaining ease of manufacture for subsequent film layers.
Solution Approach 2:
The hydrophobic layer serves as an intermediary that provides the spill prevention function. This thin layer achieves the same effect as a thicker black matrix without the manufacturing difficulties, allowing easy coverage of follow-up film layers while preventing color mixing.
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 method effectively prevents color pigment spilling and ensures uniform thickness and quality of the color filter, enhancing display quality by eliminating mura phenomena and improving the coverage of subsequent film layers.
Implementation Method 1
forming an isolation layer on the black matrix using photosensitive materials, followed by lithography
Implementation Method 2
the pigments are solidified by thermal baking process
Implementation Method 3
a hydrophobic treatment is performed on the black matrix 120 to modify the surface tension of the color pigment 130 on the black matrix 120
Data Source
AI summary
A manufacturing method of a color filter comprising the following steps is provided. At first, a transparent substrate is provided. Next, a black matrix is formed on the transparent substrate to define a plurality of pixel areas on the transparent substrate. Then, an isolation layer is formed and patterned on the black matrix and then Red/Green/Blue color filter inks are filled into each of the pixel areas separately by inkjet printing. After that, the color filter inks are dried to form color filter units and optionally the isolation layer can further be patterned to form plenty of photo spacers on the black matrix. The isolation layers prevented the color filter inks from spilling out of the pixel areas and color mixing problems during color filter inkjet fabrication. Besides, it is characterized that the color filter units can be formed with even thickness.