OLED Pixel Layout With Unequal Driving Transistors for Color Uniformity
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Solution Overview
Problem
Current OLED displays face challenges in controlling red, green, and blue light emissions due to differing emission efficiencies of their materials, leading to a need for designing pixels to manage these colors uniformly and optimizing pixel aperture ratios.
Innovation Solution
The OLED display incorporates pixels with driving transistors of varying sizes and shapes, along with a matrix arrangement of red, green, and blue pixels, where the driving transistors have different areas and the OLEDs occupy equal areas, allowing for tailored current driving and aperture ratios based on emission efficiency, with serpentine channels and alternating gate line orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixels are designed with different sizes to compensate for different emission efficiencies of red, green, and blue light emitting materials, then uniform color emission can be achieved, but pixel aperture ratio decreases
Solution Approach 1:
The patent applies local quality by making the driving transistor sizes specific to each pixel type (red, green, blue) rather than uniform. The transistor channel widths are locally adjusted according to the emission efficiency requirements of each color, allowing optimal current control for each pixel while maintaining consistent pixel electrode areas for high aperture ratio.
2Reliability
If driving transistors have different areas to match emission efficiencies, then current driving characteristics improve, but device complexity increases
Solution Approach 1:
The patent changes the physical parameters of the driving transistors, specifically the channel widths, to match the emission efficiency requirements of different color pixels. Red pixels have wider channels (1.2-1.5 times green), green pixels have medium channels, and blue pixels have narrowest channels (0.8-1.0 times green), optimizing current control for each color while maintaining a systematic design approach.
3Ease of manufacture
If all pixels occupy equal area to maintain high aperture ratio, then manufacturing simplicity is improved, but uniform color control becomes difficult due to different emission efficiencies
Solution Approach 1:
The patent maintains uniform pixel electrode areas for ease of manufacturing and high aperture ratio, while simultaneously applying local quality to the driving transistor sizes. This allows the pixel structures to be uniformly fabricated while the transistors are locally adjusted to compensate for different emission efficiencies of red, green, and blue light emitting materials.
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 configuration enables efficient light emission and uniform color mixing by matching transistor sizes to emission efficiencies, enhancing current driving characteristics and maintaining a desirable aperture ratio.
Implementation Method 1
Excitons are formed when the injected electrons and holes recombine, and emit light by discharging energy
Data Source
AI summary
An organic light emitting diode display includes a plurality of pixels. Each pixel includes a light emitting element and a driving transistor coupled to the light emitting element. The pixels may be arranged in a matrix. The pixels include first pixels, second pixels, and third pixels, the driving transistors of the first to the third pixels occupy different areas, and the light emitting elements of the first to the third pixels occupy substantially equal area.