Organic EL Illumination Device Series-Parallel Circuit Topology
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Solution Overview
Problem
Organic EL illumination devices face issues with short circuits and open circuits between anode and cathode, leading to reduced yield and reliability, especially in devices with multiple connected panels, due to non-uniform electric fields and voltage overshoot/undershoot, which can cause all panels to malfunction.
Innovation Solution
The device connects multiple organic EL panels in series circuits and then connects these series circuits in parallel between the positive and negative electrodes, allowing panels with short circuits or open circuits to be isolated while maintaining light output from unaffected panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple organic EL panels are connected in series to increase drive voltage control, then voltage control flexibility is improved, but reliability deteriorates because a short circuit or open circuit in one panel causes all panels to malfunction
Solution Approach 1:
The patent divides the series connection into multiple parallel branches, where each branch contains series-connected panels. This segmentation allows one branch to be isolated when a fault occurs, preventing complete system failure and maintaining voltage control flexibility through the remaining branches.
Solution Approach 2:
The patent incorporates protective circuits and isolation mechanisms beforehand to prevent fault propagation. When a short circuit or open circuit is detected in one panel, the isolation mechanism activates to disconnect that panel from the entire system, cushioning the impact and maintaining operation of other panels.
2Use of energy by stationary object
If the layer thickness is reduced to enable low voltage operation, then power consumption is reduced, but reliability deteriorates due to increased susceptibility to short circuits from foreign substances or unevenness
Solution Approach 1:
The patent applies different quality requirements to different regions of the thin layer. Critical areas are subjected to enhanced inspection and protective measures, while maintaining the overall thin structure for low power consumption. This localized quality enhancement protects against short circuits without sacrificing energy efficiency.
Solution Approach 2:
The patent implements protective measures beforehand, including careful control of the thin layer formation process to minimize unevenness and foreign substance contamination, and incorporating isolation mechanisms that activate when faults are detected, cushioning the inherent vulnerability of the thin structure.
3Illumination intensity
If the luminescent area is increased to improve illumination output, then brightness is improved, but reliability deteriorates due to higher probability of short circuits in the large area
Solution Approach 1:
The patent segments the large luminescent area into multiple smaller panels connected in series within parallel branches. This segmentation maintains high overall brightness while reducing the probability of short circuits in any single panel, as a fault in one small panel does not affect the entire large area.
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 ensures that all panels can continue to function even if one panel experiences a short circuit or open circuit, minimizing yield loss and reliability issues by distributing current and potential evenly across the device.
Implementation Method 1
An organic EL element or an organic EL section in an organic EL panel or the like includes an anode such as a transparent electrically-conducting layer, a cathode formed by using a metal thin layer such as aluminum and a luminescent layer including organic material. When, in the organic EL section, an electric field is generated between the anode and the cathode by applying a voltage therebetween, a hole that is a carrier is injected from the anode into the luminescent layer, and an electron that is a carrier is injected from the cathode into the luminescent layer. The electron and hole are recombined with each other in the luminescent layer to produce luminescence.
Data Source
AI summary
In the organic EL illumination device including m (m is an integer greater than 1) series circuits each of which includes n (n is an integer greater than 1) organic EL panels connected in series, each of the organic EL panels is provided with one organic EL element, a positive electrode and a negative electrode, the m series circuits are connected in parallel between the positive electrode and the negative electrode, and among the organic EL panels in the m series circuits, the organic EL panels having the same place in series connections in the direction from the positive electrode to the negative electrode are connected with each other in parallel.