OLED Pixel Structure Delta Arrangement Shadow Mask Segmentation
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Solution Overview
Problem
The existing pixel structures for electroluminescent displays, such as OLEDs, face limitations in resolution due to the design of shadow masks used in the evaporation deposition process, which restricts the density of subpixels and hence the achievable resolution.
Innovation Solution
A pixel structure with subpixels arranged in a delta formation, utilizing multiple shadow masks with T-shaped openings to deposit subpixels without overlapping, allowing for closer subpixel spacing and increased resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectangular openings are used in shadow mask for stripe pixel structure, then fabrication is simple, but gap between openings must be large to maintain structural strength, limiting subpixel density and resolution
Solution Approach 1:
The shadow mask is divided into multiple masks (first shadow mask, second shadow mask, third shadow mask), each responsible for depositing a specific color subpixel. This segmentation allows each mask to have a single large opening instead of multiple small rectangular openings, eliminating the need for gaps between openings while maintaining structural strength.
Solution Approach 2:
The invention transitions from a two-dimensional array of rectangular openings to a three-dimensional stacking approach with multiple shadow masks. Each mask is positioned at a different height and deposits material at a specific location, allowing openings to be larger without compromising resolution since the precise positioning in the vertical dimension compensates for the larger horizontal opening size.
2Device complexity
If subpixels are arranged in stripe formation, then pattern arrangement is simple, but resolution is limited due to shadow mask structural requirements
Solution Approach 1:
The single complex shadow mask with multiple rectangular openings is segmented into three simpler shadow masks, each with a single opening for one color. This segmentation simplifies the pattern arrangement for each individual mask while achieving higher resolution through the combined effect of all three masks.
Solution Approach 2:
Instead of using one mask to deposit all three colors simultaneously with multiple small openings, the invention uses three masks that each deposit one color. This partial action approach (one color per mask) allows for larger openings and better structural strength while the cumulative effect of all three deposits achieves the complete pixel structure with higher resolution.
3Manufacturing precision
If shadow mask openings are made close together to increase subpixel density, then resolution improves, but structural strength of shadow mask deteriorates
Solution Approach 1:
The shadow mask system is segmented into multiple separate masks, each with a single large opening. This eliminates the problem of gaps between multiple openings in a single mask, as each mask only needs one opening. The structural strength is maintained because each mask can be designed with sufficient material between its single opening and the mask edges, while the high subpixel density is achieved through precise positioning of the three masks relative to each other.
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 delta arrangement of subpixels enhances light mixing and display quality, overcoming the limitations of shadow mask structural strength, resulting in higher precision and increased resolution beyond 200 ppi.
Implementation Method 1
utilizing multiple shadow masks with T-shaped openings to deposit subpixels without overlapping
Implementation Method 2
evaporation deposition process
Data Source
AI summary
A method of fabricating a pixel structure for use in an electroluminescent panel includes the following steps. A substrate is provided. Three shadow masks having a plurality of first, second, and third openings patterned in an array of T shaped are respectively provided, and three evaporation processes using the three shadow masks are subsequently performed to form a plurality of first subpixel units, second subpixel units and third subpixel units respectively. One first subpixel of the first subpixel unit, one second subpixel of the second subpixel unit adjacent to the first subpixel unit, and one third subpixel of the third subpixel unit adjacent to the first subpixel unit form a display pixel unit.