OLED Subpixel Scan Line Metal Layer Aperture Ratio
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Solution Overview
Problem
In OLED displays, the addition of a sensing circuit to compensate for changes in subpixel characteristics reduces the aperture ratio and causes damage to signal and power lines during the repair process, particularly in high-resolution and large-sized displays.
Innovation Solution
The use of at least two scan lines in the circuit area, where one or more of these scan lines are formed by a metal layer different from the gate metal layer constituting the gate electrodes of transistors, allowing for improved spacing and reduced overlap with other lines, thereby increasing the aperture ratio and preventing line damage during repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensing circuit is added inside the subpixel to compensate for component characteristic changes, then the display device can maintain performance over time, but the aperture ratio of the subpixel is reduced
Solution Approach 1:
The patent introduces a time dimension by implementing dual scan lines that operate at different times. The first scan line operates during normal display, while the second scan line operates during a sensing period in a time-division manner. This temporal separation allows the sensing circuit to share the same physical space without reducing the aperture ratio, as both functions coexist in time rather than competing for space.
Solution Approach 2:
The circuit area is designed to serve multiple functions: it contains both the emission element control circuitry and the sensing circuitry. The same circuit area that would otherwise be dedicated solely to driving the emission element is now also used for sensing component characteristics, eliminating the need for separate dedicated sensing circuit space and thus preserving aperture ratio.
2Reliability
If a sensing circuit is added inside the subpixel, then component characteristic changes can be compensated, but the line load increases and repair process becomes more complex
Solution Approach 1:
The patent merges the sensing circuit with the existing driving circuitry in the circuit area. The sensing transistor and sensing line are integrated into the same circuit region that already contains the emission element control circuits. This consolidation allows sensing functionality to be added without proportionally increasing overall circuit complexity, as shared infrastructure (metal layers, insulating layers, substrate) is utilized.
Solution Approach 2:
The scan lines are segmented into multiple separate lines (first scan line and second scan line) that are spatially separated and positioned in opposite portions of the circuit area. This segmentation reduces interference between signal lines and simplifies the repair process, as damage to one scan line does not necessarily affect the other, and each can be independently repaired or replaced.
3Productivity
If multiple signal lines and electrodes are positioned close together in the circuit area, then the aperture ratio is reduced, but the line load increases and repair becomes difficult
Solution Approach 1:
The patent positions scan lines in the vertical dimension (opposite portions of the circuit area) rather than horizontally adjacent to each other. This vertical separation in the circuit area layout provides adequate spacing between signal lines while maintaining compact overall subpixel design, thus preserving aperture ratio while improving repair accessibility.
Data Source
AI summary
A display device including subpixels and at least two scan lines is disclosed. The subpixels are arranged on a substrate, and each subpixel includes an emission area, in which an emission element is disposed to emit light, and a circuit area, in which a circuit for driving the emission element is disposed. The at least two scan lines are positioned in the circuit area. One or more of the at least two scan lines are formed by a metal layer different from a gate metal layer constituting gate electrodes of transistors disposed in the circuit area.