White LED Repair for MicroLED Display Pixel Yield
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Solution Overview
Problem
The challenge in manufacturing direct view display devices using microLEDs is the high failure rate of microLED transfer to the backplane, resulting in imperfect devices, necessitating a method for repairing defective pixels.
Innovation Solution
A method involving white LEDs is introduced, where white LEDs are transferred to the backplane to repair defective pixels, comprising a substrate with n-doped and p-doped compound semiconductor layers and an active region configured to emit red, green, or blue light without color conversion materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microLED transfer process is used to manufacture direct view display devices, then productivity is improved, but manufacturing precision deteriorates due to high failure rate of microLED transfer
Solution Approach 1:
The patent applies preliminary action by preparing repair microLEDs in advance and storing them in a repair microLED array structure before defects occur. When transfer failures are detected, pre-prepared repair microLEDs are immediately transferred to defective pixel locations, eliminating the need for real-time fabrication and reducing repair time.
Solution Approach 2:
The patent changes the operational state of microLEDs by controlling their electrical parameters. Specifically, it applies forward bias to activate microLEDs and reverse bias to deactivate or repair them, enabling dynamic control of microLED functionality during transfer and repair processes.
2Reliability
If all microLEDs must be functional for device operation, then reliability is improved, but device complexity increases due to need for perfect transfer of all pixels
Solution Approach 1:
The patent segments the microLED system into functional microLEDs and repair microLEDs. The display device is divided into operational pixels and repairable pixels, with separate transfer processes for each. This segmentation allows defective pixels to be individually identified and repaired without compromising the entire device.
Solution Approach 2:
The patent creates copies of microLEDs in the form of repair microLEDs that are identical in structure and function to the original microLEDs. These repair copies are stored in a dedicated array and transferred to replace defective microLEDs, ensuring functional redundancy and enabling repair without redesigning the entire system.
3Ease of repair
If defective pixels are repaired by transferring white LED, then ease of repair is improved, but device complexity increases due to integration of different LED types
Solution Approach 1:
The patent applies universality by designing the white LED to perform multiple functions: it serves as both a repair element for defective pixels and as a functional light-emitting component. The white LED integrates red, green, and blue emitting regions, allowing it to replace multiple color subpixels and function as a complete pixel replacement unit.
Solution Approach 2:
The patent merges multiple LED functions into a single white LED structure. By combining red, green, and blue emitting regions within one white LED, the patent reduces the number of separate components needed for repair and simplifies the repair process while maintaining full color functionality.
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 approach effectively repairs defective pixels in direct view display devices, enhancing the functionality and yield of microLED-based displays by utilizing white LEDs to replace non-functional microLEDs, thereby improving the overall performance and reliability of the display devices.
Implementation Method 1
an active region disposed between the n-doped and p-doped compound semiconductor layers, the active region comprising quantum wells configured to respectively emit at least one of red, green, or blue light
Data Source
AI summary
A white LED and a method of repairing a light emitting device including, the method including colored light emitting diodes (LEDs) configured to emit different colors of light and arranged in pixels on a backplane of the device, the method including: determining whether each pixel is a functional pixel or a defective pixel; and repairing the defective pixels by transferring white LEDs to the backplane in each defective pixel.