Segmented Electroluminescent Device with Resistive Interconnects
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Solution Overview
Problem
Existing electroluminescent devices, such as OLEDs, face challenges when directly driven from mains power due to high peak currents, mains current harmonics exceeding regulation limits, and varying current values with voltage changes, requiring additional circuit elements and complex heat management in prior art solutions.
Innovation Solution
A segmented electroluminescent device with a resistive interconnect layer connecting anode and cathode of neighboring segments, featuring a transparent anode and opaque cathode, and an isolation layer to increase resistance and capacitance, allowing direct connection to mains power while managing heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If OLED devices are connected in series to achieve required resistance for mains driving, then the device can be directly connected to mains power, but the OLED peak current becomes much higher than the average value and current values vary greatly with mains voltage variation
Solution Approach 1:
The device is divided into multiple segments with individual electrodes and electroluminescent layers, where each segment can be independently controlled. This segmentation allows the total resistance to be distributed across multiple elements, enabling direct mains connection while maintaining stable current through the resistive interconnect layers that limit peak currents in each segment.
Solution Approach 2:
Resistive interconnect layers are introduced as intermediary elements between the electrodes and segments. These interconnect layers have controlled resistance values that act as ballast resistors, limiting peak currents and stabilizing the overall device operation when connected to mains power, thereby eliminating the need for external ballast circuits.
2Reliability
If additional circuit elements and ballast are used to operate OLED devices from mains, then current stability is improved, but device complexity and heat management requirements increase
Solution Approach 1:
The ballast resistance function is merged into the device structure itself through the resistive interconnect layers, eliminating the need for separate external ballast circuits. The interconnect layers serve dual purposes: electrical connection between segments and current limiting, thereby reducing overall device complexity while maintaining current stability.
Solution Approach 2:
The resistive interconnect layers perform multiple functions simultaneously: they provide electrical interconnection between segments, act as ballast resistors for current stabilization, and contribute to heat distribution across the device. This multi-functionality reduces the need for additional dedicated components.
3Reliability
If additional circuit elements and ballast are used to operate OLED devices from mains, then current stability is improved, but heat management efforts increase
Solution Approach 1:
By segmenting the device into multiple sections with distributed resistive interconnect layers, the heat generation is spread across multiple locations rather than concentrated in a single ballast circuit. This distribution facilitates more effective heat dissipation and reduces thermal management complexity.
Solution Approach 2:
The resistive interconnect layers that generate heat as a byproduct of current limiting are strategically positioned and designed to distribute this thermal energy across the device structure. The heat that would otherwise be waste is converted into a distributed thermal profile that is easier to manage and can even improve uniformity of operation across segments.
4Device complexity
If segments are connected with direct electrode contact, then device structure is simplified, but resistance control and ballast function are lost
Solution Approach 1:
Resistive interconnect layers are introduced as intermediary elements between directly contacting electrodes. These interconnect layers maintain the electrical connection necessary for segment operation while providing controlled resistance to regulate current flow, thereby preserving both structural simplicity and current control functionality.
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
The solution enables efficient direct connection to mains power, reducing flicker and heat management efforts, and improving device sealing by distributing ballast resistance across multiple segments, thus addressing the limitations of prior art solutions.
Implementation Method 1
The resistive interconnect layer is adapted to connect an anode and a cathode of two neighbouring segments and, contrary to prior art, to add a ballast resistance
Implementation Method 2
Electroluminescent devices comprise electroluminescent material that is capable of emitting light when a current is passed through it. Light is produced by radiative recombination of holes and electrons inside the electroluminescent material.
Implementation Method 3
an isolation layer to increase resistance and capacitance, allowing direct connection to mains power while managing heat effectively
Data Source
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AI summary
A segmented electroluminescent device (100) with resistive interconnect layers (102), each segment (104,104', 104'') comprising an electroluminescent layer (110) arranged in between a first (106) and a second electrode (108) layer. The segments (104, 104', 104'') are connected via resistive interconnect layers (102), the resistive interconnect layers having a larger square resistance than the second electrode layer. The resistive interconnect layers (102) add a ballast resistance to the electroluminescent device such that no additional electric ballast is needed. As the electric ballast is divided over multiple layers the problem of a heat management for the electric ballast becomes less important. By adding an isolation layer (122) the surface of the resistive interconnect layers (102) can be increased to almost the whole surface of the electroluminescent device (100). The system of the electrode layer(108), the isolating layer (122) and the resistive layer (102) functions as a capacitor.