Quad Cell OLED Power Distribution via Shared Buses
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Solution Overview
Problem
Active-matrix OLED devices face challenges with power distribution, leading to uneven luminance and undesirable imaging artifacts due to unintended voltage drops along power and return lines, which are exacerbated by the finite resistance of these lines and the need for high currents.
Innovation Solution
The solution involves arranging light-emitting elements in quad cells with shared electrical buses and cross-connections, allowing for optimized power distribution and aperture ratio, with reflected layouts to improve current uniformity and reduce manufacturing tolerance spacing, thereby enhancing light-emission uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high currents are used to drive OLED elements, then light emission intensity is improved, but voltage drops along power lines increase causing uneven luminance
Solution Approach 1:
The patent divides the display into quad cells (groups of four pixels) with shared power and return lines. This segmentation allows current to be distributed more efficiently across multiple pixels through shared conductors, reducing the relative impact of voltage drops on individual pixels while maintaining high light emission intensity.
Solution Approach 2:
The patent implements reflected layouts where pixels are positioned symmetrically around power and return line intersections, creating more equipotential regions. This geometric arrangement ensures that pixels at different locations experience more uniform voltage conditions, addressing the luminance uniformity problem while allowing high drive currents.
2Reliability
If power line width is increased to reduce resistance, then voltage drop is reduced, but aperture ratio decreases
Solution Approach 1:
The patent combines power and return lines into shared conductors that serve multiple pixels through the quad cell structure. This merging allows the same conductor to carry current for multiple pixels, effectively distributing power without requiring proportionally wider lines for each pixel, thus maintaining aperture ratio while improving voltage distribution.
Solution Approach 2:
The shared power and return lines serve multiple functions by providing electrical connection to multiple pixels simultaneously. This multi-functionality allows the power distribution network to achieve better voltage uniformity without increasing the total conductor area, preserving the aperture ratio.
3Reliability
If pixels are positioned closer to power lines, then power distribution is improved, but manufacturing tolerance spacing is increased
Solution Approach 1:
The patent uses reflected layouts that create asymmetric positioning of pixels relative to power and return lines within each quad cell. This asymmetric yet symmetric arrangement optimizes the distance from power lines while maintaining manufacturability, achieving good power distribution without excessive tolerance requirements.
Solution Approach 2:
By organizing pixels into quad cells with specific geometric arrangements around power line intersections, the patent segments the display into manageable units. This segmentation allows optimization of power distribution within each cell while keeping manufacturing tolerances reasonable through the structured layout.
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 arrangement improves power distribution and light-emission uniformity, reducing visible artifacts and allowing for larger display areas while maintaining an equivalent aperture ratio, thus addressing the limitations of existing OLED technologies.
Implementation Method 1
each comprising a first electrode and a second electrode, having one or more electroluminescent layers formed there-between
Data Source
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AI summary
An active-matrix electroluminescent device, comprising: light-emitting elements (20a, 20b, 20c, 2Od) laid out over a substrate, electrical buses (14a, 14b) carrying a common signal connected to the light-emitting elements; and electrical cross-connections (12a, 12b) intersecting and electrically connecting the plurality of electrical buses. The light-emitting elements are arranged in groups, each group forming a quad cell (4a, 4b, 4c, 4d) of four neighboring light-emitting elements arranged around intersections of the electrical buses and cross-connections, each of the light-emitting elements of each quad cell connected to the electrical bus or electrical cross-connection separating the light-emitting elements of the quad cell, each quad cell shares a common electrical bus or cross-connection with an adjacent quad cell, and adjacent quad cells sharing a common electrical bus are not separated by a common cross-connection and neighboring quad cells sharing a common cross-connection are not separated by a common electrical bus.