Pad-Connected Display Pixel Layout for Defect-Tolerant Emission
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Solution Overview
Problem
Display devices using light emitting elements face issues with defects such as short circuits and disconnections, which can lead to entire pixels failing to emit light due to the connection relationships of the light emitting elements.
Innovation Solution
The display device incorporates light emitting elements connected in series and parallel configurations, with a specific structure including a substrate, insulating layers, contact electrodes, and a pad unit to ensure robustness against defects, allowing other elements to continue emitting light even if some experience short circuits or disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light emitting elements are connected in series to improve luminance and lifetime, then the pixel performance is enhanced, but the reliability deteriorates because a defect in any element causes the entire pixel to fail
Solution Approach 1:
The pixel is divided into multiple sub-pixels, each containing separate light emitting elements that can be independently controlled. This segmentation allows the pixel to maintain partial functionality even when some elements fail, resolving the contradiction between series connection benefits and reliability concerns
Solution Approach 2:
The patent changes the electrical connection parameters from pure series to a hybrid configuration combining series and parallel connections. This parameter modification enables the system to achieve both high luminance (through series connections within sub-groups) and improved reliability (through parallel paths that bypass defective elements)
2Reliability
If light emitting elements are connected in parallel to improve reliability, then the pixel remains functional despite defects, but the luminance and lifetime performance deteriorates
Solution Approach 1:
The pixel is divided into multiple sub-pixels with independent light emitting elements, allowing parallel connection of separate elements while maintaining the ability to achieve high luminance through selective activation and series connections within sub-groups
Solution Approach 2:
The patent creates a composite connection structure combining series and parallel configurations, leveraging the advantages of both connection types to achieve simultaneously high reliability and luminance performance
3Device complexity
If a simple connection structure is used to reduce device complexity, then manufacturing is easier, but the robustness against defects deteriorates
Solution Approach 1:
The pixel is divided into multiple sub-pixels with independent light emitting elements, allowing parallel connection of separate elements while maintaining the ability to achieve high luminance through selective activation and series connections within sub-groups
Solution Approach 2:
The contact electrodes and insulating layers are designed to serve multiple functions: electrical connection, defect isolation, and structural support. This multi-functionality reduces the need for additional components, maintaining manufacturing simplicity while enhancing robustness
Data Source
AI summary
A display device includes a substrate including a display area and a non-display area, a pixel located in the display area, a pad unit on one side of the non-display area, and a driver connected to the pixel. The pixel includes a first insulating layer, a first light emitting element on the first insulating layer, a second insulating layer on the first light emitting element and exposing one end portion and another end portion of the first light emitting element, a first contact electrode on the second insulating layer and connected to the one end portion of the first light emitting element, and a second contact electrode on the second insulating layer and connected to the other end portion of the first light emitting element. The pad unit includes a pad metal layer, a first pad insulating layer, a second pad insulating layer, and a pad electrode.