Light Emitting Element Series Cell Defect Detection
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Solution Overview
Problem
Existing light emitting elements with multiple cells connected in series face challenges in evaluating the electrical properties of each cell, making it difficult to detect defects like leakage current, which can lead to reliability issues.
Innovation Solution
A light emitting element configuration that includes insulating substrates, light emitting cells with n-side and p-side semiconductor layers, light-reflective electrodes, and strategically placed openings in insulating films to allow for separate electrical property checks of each cell through external connection points, enabling accurate defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple light emitting cells are connected in series by a wiring electrode, then the light emitting element can function as a series circuit, but it becomes difficult to evaluate the electrical properties of each individual cell and detect defects like leakage current
Solution Approach 1:
The patent divides the continuous insulating film into multiple segmented regions by forming through-holes at specific positions. This segmentation allows individual access to the n-side semiconductor layer of each light emitting cell, enabling separate electrical property evaluation of each cell while maintaining the series circuit configuration. The through-holes create discrete measurement points that correspond to each cell's n-side contact, facilitating defect detection without requiring cell disconnection.
Solution Approach 2:
The patent introduces an intermediary measurement structure consisting of through-holes in the insulating film and additional electrode connections. These intermediaries provide access points to the n-side semiconductor layer, allowing electrical measurements to be performed on each cell individually. The intermediary structures act as bridges between the external measurement equipment and the internal cell structures, enabling defect detection while preserving the series circuit operation.
2Measurement precision
If light emitting cells are connected in series, then the device can operate with reduced current requirements, but individual cell electrical properties cannot be checked making leakage current detection impossible
Solution Approach 1:
The insulating film is segmented into multiple regions with through-holes positioned to provide individual access to each light emitting cell's n-side semiconductor layer. This segmentation enables precise electrical measurements of each cell independently, allowing accurate detection of leakage current and other electrical defects while maintaining the series circuit configuration.
Solution Approach 2:
The light emitting cells themselves serve as the measurement subjects through the through-hole access structure. By providing direct access to the n-side semiconductor layer of each cell, the structure enables self-diagnosis capability where each cell's electrical properties can be evaluated independently without requiring external disconnection or complex testing equipment.
3Reliability
If a continuous insulating film covers all light emitting cells, then device protection and electrical isolation are improved, but access to individual cell n-side layers for measurement is blocked
Solution Approach 1:
The continuous insulating film is segmented by forming through-holes at specific positions corresponding to each light emitting cell's n-side contact region. This segmentation maintains electrical isolation between cells while creating controlled access points for measurement. The insulating film remains intact in most regions, preserving protection and isolation functions, while the through-holes provide necessary measurement access.
Solution Approach 2:
The insulating film exhibits different properties at different locations: in most regions it provides continuous protection and electrical isolation, while at specific through-hole positions it provides localized access to the n-side semiconductor layer. This local differentiation allows the film to simultaneously fulfill both protection and measurement access functions without compromising either.
Data Source
AI summary
The light emitting element includes: first and second light emitting cells each including an n-side semiconductor layer, an active layer and a p-side semiconductor layer; a first insulating film covering the first and second light emitting cells, and provided with first p-side and first n-side openings; a wiring electrode connected to the first light emitting cell at the first n-side opening, and connected to the second light emitting cell at the first p-side opening; a first electrode connected to the first light emitting cell; a second electrode connected to the second light emitting cell; a second insulating film provided with a second p-side opening formed above the first electrode, a second n-side opening formed above the second electrode, and a third opening formed above the wiring electrode; a first external connection portion connected to the first electrode; and a second external connection portion connected to the second electrode.