LED Display Pixel Array with Inclined Passivation for Light Extraction
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Solution Overview
Problem
Existing display apparatuses using LEDs as pixels face challenges in achieving high luminance and compactness while maintaining optical efficiency, particularly in the design and arrangement of electrodes and passivation layers to optimize light extraction.
Innovation Solution
The display apparatus incorporates a pixel array with LED cells stacked sequentially using conductivity-type semiconductor layers, wavelength converters, and a partition structure in the upper semiconductor layer, along with inclined passivation and reflective layers to enhance light extraction efficiency, and a hybrid bonding method for electrode connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional flat passivation layers and electrode arrangements are used, then manufacturing is simpler, but light extraction efficiency is insufficient
Solution Approach 1:
The patent applies curvature by forming the passivation layer with inclined side surfaces instead of flat surfaces. This curved geometry redirects light paths and reduces total internal reflection at interfaces, thereby improving light extraction efficiency while maintaining manufacturing feasibility through standard semiconductor processing techniques.
Solution Approach 2:
The patent transitions from a two-dimensional planar electrode arrangement to a three-dimensional configuration where electrodes are positioned at inclined angles relative to the LED cell surfaces. This dimensional change allows electrodes to collect light from multiple angles, enhancing extraction efficiency without complicating the manufacturing process.
2Loss of energy
If electrodes are positioned to maximize light extraction, then optical efficiency improves, but device complexity increases
Solution Approach 1:
The passivation layer serves multiple functions simultaneously: it provides electrical insulation, structural support, and optical management through its inclined geometry. This multi-functionality reduces the need for additional dedicated components, thereby improving optical efficiency without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the functions of the passivation layer and the light extraction structure into a single integrated component. The inclined side surfaces of the passivation layer combine electrical isolation with optical redirection, simplifying the overall device architecture while enhancing performance.
3Volume of moving object
If compact LED cell design is used, then device size is reduced, but light extraction efficiency decreases
Solution Approach 1:
The inclined side surfaces of the passivation layer in compact LED cells create curved light paths that extract more light from the small device volume. This curvature effect allows efficient light extraction even when the overall device size is reduced, maintaining optical performance in compact form factors.
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 configuration improves light extraction efficiency and enables the creation of a miniaturized, high-resolution display device with optimized electrode arrangements and bonding techniques.
Implementation Method 1
wavelength converters on the LED cells
Implementation Method 2
an upper semiconductor layer on the LED cells and having a partition structure surrounding side surfaces of the wavelength converters and separating the wavelength converters from each other
Implementation Method 3
a passivation layer on side surfaces of the LED cells and having external side surfaces inclined to increase a thickness in direction toward the wavelength converters
Implementation Method 4
reflective layers between the first electrode and the second electrodes along the passivation layer on the side surfaces of the LED cells and having surfaces inclined toward outside of the LED cells
Data Source
AI summary
A display apparatus includes: a circuit substrate; and a pixel array on the circuit substrate and including a plurality of pixels. The pixel array includes: light emitting diode (LED) cells constituting the plurality of pixels, each of the LED cells including a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer; wavelength converters on the LED cells; an upper semiconductor layer on the LED cells and having a partition structure; a passivation layer on side surfaces of the LED cells; a first electrode along a region of the LED cells to have a grid shape; second electrodes connected to the second conductivity-type semiconductor layers; and reflective layers between the first electrode and the second electrode along the passivation layer on the side surfaces of the LED cells and having surfaces inclined toward outside of the LED cells.