Single-Substrate Microcavity Display for Transmittance Correction
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Solution Overview
Problem
Conventional liquid crystal displays require two substrates, leading to increased weight, thickness, and cost, as well as a long processing time, and suffer from contrast ratio deterioration due to differences in transmittance among color filters, necessitating separate voltage control for each color filter.
Innovation Solution
A single-substrate display device with varying microcavity thickness for each pixel area, achieved by positioning color filters differently, allowing for corrected transmittance without additional masks or voltage control units, using a substrate with pixel electrodes, roof layers, and a liquid crystal layer in microcavities, where the cell gap is adjusted for each color filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two substrates are used in liquid crystal display, then the display can be formed with conventional structure, but the weight, thickness, cost, and processing time increase
Solution Approach 1:
The patent merges two separate substrates into a single substrate structure. The first substrate contains pixel electrodes and the second substrate contains color filters and common electrode, but both are integrated on one substrate, eliminating the need for a second separate substrate while maintaining all necessary functional layers for liquid crystal display operation.
Solution Approach 2:
The single substrate serves multiple functions that were previously distributed across two substrates. It provides the base for pixel electrodes, supports the liquid crystal layer, carries color filters, and hosts the common electrode, thereby reducing overall device complexity while maintaining display functionality.
2Reliability
If two substrates are used in liquid crystal display, then the display can be formed with conventional structure, but the processing time increases
Solution Approach 1:
By combining the functions of two substrates into one, the patent reduces the number of manufacturing steps. Instead of separately forming and assembling two substrates, all layers including pixel electrodes, liquid crystal, color filters, and common electrode are formed on a single substrate, significantly reducing processing time.
3Ease of operation
If the same voltage is applied for each sub pixel with varying transmittance of color filters, then the liquid crystal display can operate, but the contrast ratio deteriorates
Solution Approach 1:
The patent applies different cell gap dimensions to different pixel regions corresponding to different color filters. Specifically, the cell gap is set to 2.5-3.5μm for red pixels, 3.0-4.0μm for green pixels, and 3.5-4.5μm for blue pixels. This local variation in physical dimensions compensates for the different transmittance characteristics of each color filter, enabling uniform contrast ratio across all colors without requiring separate voltage control.
4Reliability
If different voltages are applied for each color filter to account for transmittance differences, then the contrast ratio can be maintained, but a separate voltage control unit is required
Solution Approach 1:
Instead of changing voltage parameters for each color filter, the patent changes the physical parameter of cell gap dimension. By adjusting the cell gap thickness according to the transmittance characteristics of each color filter (smaller gap for high transmittance colors like red, larger gap for low transmittance colors like blue), the optical performance is equalized without requiring complex voltage control circuits.
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 solution reduces weight, thickness, and processing time while maintaining image quality by correcting transmittance differences among color filters, eliminating the need for separate voltage control units and additional processing steps.
Implementation Method 1
The liquid crystal display generates an electric field in the liquid crystal layer by applying a voltage across the field generating electrodes
Implementation Method 2
This controls polarization of incident light, thereby displaying images
Implementation Method 3
A cell gap of the microcavity corresponding to the third pixel area is smaller than cell gaps of the microcavities respectively corresponding to first pixel area and second pixel area
Data Source
AI summary
A display device including: a substrate including first, second, and third pixel areas; a plurality of pixel electrodes positioned on the substrate within each of the first, second, and third pixel areas; and a plurality of roof layers each facing a respective one of the pixel electrodes, ones of the roof layers positioned to be spaced apart from respective ones of the pixel electrodes with a plurality of microcavities therebetween, the microcavities positioned to correspond to each of the first, second, and third pixel areas. The roof layer includes first and second color filter layers positioned corresponding to the first pixel area and the second pixel area and a third color filter layer positioned below the liquid crystal layer, and a cell gap of the microcavity corresponding to the third pixel area is smaller than cell gaps of the microcavities corresponding to the first and second pixel areas.