μLED Subpixel Redundancy Layout for Higher Display Yield
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Solution Overview
Problem
The high manufacturing costs and yield reduction issues in self-light emitting apparatuses due to the need for a high yield of micro light emitting diode (μLED) elements and their precise mounting, especially for high-resolution displays, where defects can significantly impact the production process.
Innovation Solution
A self-light emitting apparatus design that incorporates a backplane with target regions containing both basic and redundant cells of μLED elements, where the redundant cells emit the same color as the basic cells, and are integrated with a smaller array pitch, allowing for increased redundancy and reduced yield loss due to defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high number of μLED elements are arrayed for high-resolution display, then display quality is improved, but manufacturing cost increases and yield reduction occurs due to the need for high precision mounting and high element yield
Solution Approach 1:
The patent applies preliminary action by forming redundant cells in advance during the μLED element array formation process. These redundant cells are pre-positioned to compensate for potential defects, so that when defects occur during mounting or operation, the display can still maintain quality without requiring rework or replacement of the entire array.
Solution Approach 2:
The patent implements beforehand cushioning by incorporating redundant cells that serve as a buffer against manufacturing defects. The redundant cells are strategically placed to cover potential defect areas, providing a cushion that prevents yield reduction when defects occur during the high-precision mounting process of μLED elements.
2Productivity
If redundant cells are added to compensate for defects, then yield loss is reduced, but device complexity increases
Solution Approach 1:
The patent merges the basic cells and redundant cells into a unified μLED element array structure. Both cell types share the same formation process, electrical connection method, and physical layout, allowing the system to maintain simplicity while incorporating redundancy. The redundant cells are integrated seamlessly into the existing array architecture rather than being added as separate complex components.
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 design effectively reduces yield loss by ensuring that even if a defect occurs in a basic cell, the redundant cell can compensate, maintaining display quality and reducing manufacturing costs through efficient LED element mounting and defect management.
Implementation Method 1
The OLED displays an image or a video in the following manner: a current optionally controlled by the thin film transistor is applied between the cathode and the anode to change luminance. The OLED employs the following principle: electrons injected through the cathode and electron holes injected through the anode are combined in the light emitting layer via the electron transport layer and the electron hole transport layer to excite light emitting materials of the light emitting layer, and light is emitted when the light emitting materials return back to the ground state from the excited state.
Data Source
AI summary
The present disclosure has an object to hinder reduction of a yield due to a failure in an LED element or a mounting failure in a self light emitting apparatus. In a self light emitting apparatus, each pixel includes one basic cell and at least one redundant cell as a subpixel. The redundant cell includes an LED element that emits light of a color the same as at least one LED element out of LED elements included in the basic cell. A plurality of subpixels included in each pixel are configured as a subpixel group being an assembly that includes a plurality of LED elements being integrated. An array pitch of the subpixels in the subpixel group is smaller than an array pitch of the subpixels in adjacent ones of a plurality of subpixel groups.