Light Emitting Device Electrode Segmentation for Uniform Luminance
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Solution Overview
Problem
The existing light emitting devices face challenges with luminance non-uniformity due to variations in electric potential across the substrate, caused by resistance issues in the common electrode, and the need for a larger window frame region to accommodate positioning tolerance, which hinders device miniaturization.
Innovation Solution
The design includes a light emitting device with a common electrode that covers the entire effective region and an auxiliary electrode with a lower resistance, positioned to extend through gaps between light emitting elements, using a highly accurate mechanism, and an insulating layer that prevents breakage or cracking, allowing for reduced window frame size and minimized luminance non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the common electrode is formed uniformly to cover the entire effective region, then the tolerance of positioning is improved, but the window frame region becomes larger
Solution Approach 1:
The electrode system is segmented into two functional parts: the common electrode that covers only the effective region, and the auxiliary electrode that extends into the peripheral region. This segmentation allows the common electrode to be formed with relaxed positioning tolerance while the auxiliary electrode handles the peripheral connections, reducing the window frame region size.
Solution Approach 2:
The auxiliary electrode is positioned in a different spatial arrangement, extending from the peripheral region toward the effective region but stopping before the light emitting elements. This dimensional differentiation allows the common electrode to be smaller while maintaining electrical connectivity through the auxiliary electrode in the peripheral dimension.
2Manufacturing precision
If the auxiliary electrode is formed using a highly accurate positioning mechanism, then the positioning precision is improved, but the device complexity increases
Solution Approach 1:
The auxiliary electrode is formed in advance during the same manufacturing process as the light emitting elements, using the same alignment references. This preliminary action eliminates the need for separate high-precision positioning mechanisms, as the auxiliary electrode's position is determined by the standard manufacturing alignment process.
Solution Approach 2:
The auxiliary electrode serves dual functions: it provides electrical connection in the peripheral region and automatically positions itself relative to the light emitting elements through the standard manufacturing alignment process. This self-service capability eliminates the need for additional positioning mechanisms.
3Reliability
If the insulating layer has a step, then the circuit element insulation is improved, but the electrode may break or crack
Solution Approach 1:
The common electrode is designed to extend beyond the light emitting elements into the peripheral region, where it is covered by the insulating layer. This beforehand extension provides a cushioning effect, ensuring that even if the insulating layer has steps, the electrode material is present to bridge potential gaps and prevent breakage or cracking.
Solution Approach 2:
The electrode system uses a composite approach where the common electrode material extends into the peripheral region and works in conjunction with the insulating layer. This composite structure ensures that the electrode maintains integrity across the step transition, combining the conductive material's continuity with the insulating layer's protective function.
Data Source
AI summary
A light emitting device includes a substrate, a plurality of light emitting elements, an element layer, an auxiliary electrode, and an insulating layer. An effective region in which the plurality of light emitting elements are arranged and a peripheral region that surrounds the effective region are provided on the substrate. Each of the light emitting elements includes a first electrode, a second electrode and a light emitting layer located between the first electrode and the second electrode. A circuit element is arranged in the element layer to control emission of light of the light emitting elements. The auxiliary electrode is electrically connected to the second electrode. The second electrode covers the effective region and is formed uniformly so as to extend into the peripheral region. The auxiliary electrode extends through a gap between adjacent light emitting elements in the effective region and is formed partly in the peripheral region.