Recessed Anode Electrodes for LED Light Extraction
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Solution Overview
Problem
Existing illumination devices using light emitting diodes (LEDs) face challenges in efficiently outputting light from side surfaces to the image display surface, leading to reduced light extraction efficiency.
Innovation Solution
The illumination device incorporates a translucent substrate with light emitting elements, anode electrodes featuring recessed structures, and a cathode electrode configuration that includes a coupling layer and a light shielding layer to direct light emitted from the LEDs towards the display surface, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat plate reflective layers are used, then the structure is simple, but light extraction efficiency deteriorates because side surface light cannot be directed to the display surface
Solution Approach 1:
The anode electrode is divided into multiple first partial anode electrodes with recessed structures, each corresponding to individual light emitting elements. This segmentation allows light from different LED positions (including side surfaces) to be independently reflected and directed toward the display surface, improving light extraction efficiency while maintaining manufacturing feasibility through modular construction
Solution Approach 2:
The invention transitions from a two-dimensional flat plate reflective layer to a three-dimensional recessed structure. The recessed portions create vertical depth and angular surfaces that can reflect light from multiple directions, particularly capturing side surface emission from LEDs and redirecting it toward the display surface, thereby resolving the light extraction efficiency problem
2Reliability
If larger anode electrodes are used to cover more light emitting elements, then electrical coupling is improved, but light shielding capability deteriorates due to increased electrode area blocking light
Solution Approach 1:
The anode electrode is segmented into first partial anode electrodes with recessed structures and second partial anode electrodes for coupling. This segmentation reduces the continuous electrode area that would block light, while maintaining electrical connectivity through the distributed partial electrodes and coupling structures, thus resolving both electrical coupling and light shielding concerns
Solution Approach 2:
Different portions of the anode electrode structure serve different functions: the first partial anode electrodes with recessed structures are positioned to reflect light toward the display surface, while the second partial anode electrodes provide electrical coupling between segments. This local differentiation allows simultaneous optimization of light extraction and electrical connectivity without compromise
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 significantly improves light extraction efficiency by effectively directing light from the LEDs to the display surface, resulting in a brighter and more efficient illumination device with reduced light leakage and improved contrast ratio.
Implementation Method 1
a plurality of light emitting elements LED that is provided to one surface SUTa of the translucent substrate SUT
Implementation Method 2
the anode electrode includes: a plurality of first partial anode electrodes ADa having recessed structures in which the light emitting elements are arranged
Data Source
AI summary
According to an aspect, an illumination device configured to be arranged opposing an image display surface of a reflective display device, includes: a translucent substrate; a plurality of light emitting elements that is provided to the translucent substrate; an anode electrode that is electrically coupled to the light emitting elements; and a cathode electrode that is electrically coupled to the light emitting elements. The anode electrode includes: a plurality of first partial anode electrodes having recessed structures in which the light emitting elements are arranged; and a second partial anode electrode that has a width less than widths of the first partial anode electrodes and couples the first partial anode electrodes.