LED Array Current Spreading via Series Pad Layout
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Solution Overview
Problem
Existing light-emitting diode (LED) arrays face challenges in achieving efficient current spreading and uniformity, which affects their luminous efficiency and light extraction, especially when designed for high driving voltages and compact layouts.
Innovation Solution
The design includes a substrate with multiple light-emitting units arranged in a two-dimensional array, each comprising a p-type and n-type semiconductor layer with an active layer, and electrical connections that extend from pads to connect adjacent units in series, using wafer transfer and bonding methods for improved light-extraction and heat dispersion, along with specific pad and connection layouts to enhance current spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED arrays are designed for high driving voltages with compact layouts, then power consumption is reduced and volume is decreased, but current spreading becomes inefficient and current uniformity deteriorates
Solution Approach 1:
The LED array is divided into multiple independently controllable LED units arranged in a matrix pattern, with each unit having its own current path through series-connected anodes and cathodes. This segmentation allows current to distribute uniformly across multiple parallel paths, preventing current crowding while maintaining compact high-voltage operation.
Solution Approach 2:
The patent transitions from traditional linear or simple grid layouts to a two-dimensional matrix arrangement where current flows in both horizontal and vertical dimensions. The anodes and cathodes are arranged in alternating rows and columns, creating a multi-dimensional current distribution network that enhances current spreading efficiency across the compact array.
2Volume of moving object
If LED arrays are designed for high driving voltages with compact layouts, then device volume is decreased, but light extraction efficiency deteriorates
Solution Approach 1:
The patent applies different structural characteristics to different regions of the LED array. Each LED unit within the matrix maintains optimized light-extraction features such as dome-shaped encapsulants or textured surfaces, while the overall array achieves compactness through the matrix arrangement. This local optimization ensures high light extraction efficiency is preserved in each unit despite the compact overall design.
3Productivity
If manufacturers design various electrode layouts to satisfy high driving voltage requirements, then production efficiency is improved, but device complexity increases
Solution Approach 1:
The matrix arrangement of anodes and cathodes serves multiple functions simultaneously: it provides high driving voltage through series connections, enables uniform current distribution through parallel paths, achieves compact form factor through two-dimensional packing, and simplifies manufacturing through regular alternating patterns. This universal structure eliminates the need for complex custom electrode designs while maintaining all desired performance characteristics.
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 current spreading and luminous efficiency, allowing the LED array to operate effectively under high driving voltages while maintaining a compact and efficient light-emitting area, addressing the challenges of current crowding and light extraction.
Implementation Method 1
a plurality of electrical connections formed on the plurality of light-emitting units, electrically connecting each two of the light-emitting units adjacent
Implementation Method 2
each of the plurality of light-emitting unit includes a first-type semiconductor layer, a second-type semiconductor layer and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer
Data Source
AI summary
A light-emitting device, including a substrate; a plurality of light-emitting units formed on the substrate, wherein the plurality of light-emitting units include a first light-emitting unit; a second light-emitting unit; and a group of light-emitting units formed between the first light-emitting unit and the second light-emitting unit, wherein each of the plurality of light-emitting unit includes a first-type semiconductor layer, a second-type semiconductor layer and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a plurality of electrical connections formed on the plurality of light-emitting units, electrically connecting each two of the light-emitting units adjacent; a first pad formed on the first light-emitting unit; a second pad and a third pad formed on the second light-emitting unit; wherein one of the plurality of electrical connection connects and extends from the second pad.