OLED Pixel Circuit Layout for Display Uniformity
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Solution Overview
Problem
In OLED display devices, striped display unevenness occurs due to misalignment during the fabrication of pixel circuits, leading to alternating bright and dark subpixel columns when displaying a single color at the same gradation level, which affects image quality.
Innovation Solution
The layout of pixel circuits is optimized by sharing power lines between adjacent circuits, with driving transistors positioned symmetrically relative to the power lines to minimize parasitic capacitance variations caused by misalignment, ensuring consistent luminance across subpixels of the same color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If power lines are shared between adjacent pixel circuits to reduce wiring space, then device area is reduced, but display unevenness occurs due to misalignment during fabrication
Solution Approach 1:
The patent applies asymmetry by intentionally designing the pixel circuit layout to be asymmetric with respect to the shared power line. Specifically, pixel circuits on opposite sides of a power line are positioned at different distances from it, creating an asymmetric configuration that compensates for misalignment effects during fabrication, thereby reducing display unevenness while maintaining space efficiency
Solution Approach 2:
The patent implements local quality by varying the positioning of pixel circuits relative to shared power lines based on their specific location. Each pixel circuit is positioned according to its local requirements to minimize parasitic capacitance variations, with circuits on opposite sides of a power line placed at different distances to achieve uniform display characteristics across the display region
2Ease of manufacture
If pixel circuits are positioned symmetrically relative to shared power lines, then manufacturing alignment is easier, but parasitic capacitance variations cause display unevenness
Solution Approach 1:
The patent deliberately introduces asymmetry in the pixel circuit positioning relative to shared power lines. Instead of symmetric placement, pixel circuits on opposite sides of a power line are positioned at different distances, creating an asymmetric layout that compensates for misalignment and reduces parasitic capacitance variations, thereby improving luminance uniformity
3Adaptability or versatility
If the number of elements in pixel circuit is increased to attain higher functionality, then device functionality is improved, but area occupied by elements increases
Solution Approach 1:
The patent applies merging by having adjacent pixel circuits share common power lines. This consolidation of wiring resources reduces the total wiring space required, allowing pixel circuits with higher functionality and more elements to be accommodated within a smaller overall area, thereby resolving the contradiction between functionality and area
Data Source
AI summary
A display device includes power lines, first driving transistors on a first side of each of the power lines, second driving transistors on a second side of each of the power lines, light-emitting elements of a first color, a second color and a third color. A first driving transistor of a first power line drives a light-emitting element of the first color. A second driving transistor of the first power line drives a light-emitting element of the second color. A first driving transistor of a second power line drives a light-emitting element of the third color. A second driving transistor of the second power line drives a light-emitting element of the second color. A first driving transistor of a third power line drives a light-emitting element of the first color. A second driving transistor of the third power line drives a light-emitting element of the third color.