Organic EL Display Bus Line Feedback Voltage Regulation
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Solution Overview
Problem
Conventional organic EL display apparatuses face issues with uneven voltage distribution in the bus line due to varying pixel currents, leading to luminance inconsistencies, especially as the size of the display increases and the frame size decreases, making it challenging to maintain even luminance across the screen.
Innovation Solution
The implementation of a feedback circuit unit that generates an output voltage and supplies it to the power supply bus line, using a reference voltage to regulate the voltage at the connecting parts of the bus line, ensuring it remains even by compensating for resistance and current-induced voltage drops, thereby maintaining target voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low resistance bus line is provided to reduce voltage unevenness, then voltage distribution is improved, but the size of the frame increases
Solution Approach 1:
The patent introduces a feedback circuit unit that monitors the voltage at the bus line and dynamically adjusts the output voltage to compensate for voltage drops. This allows the use of standard resistance bus lines while maintaining uniform voltage distribution through active feedback control, eliminating the need to increase frame area to reduce resistance.
2Manufacturing precision
If the bus line resistance is reduced by increasing frame size, then voltage unevenness is reduced, but the display apparatus size increases
Solution Approach 1:
The feedback circuit unit dynamically compensates for voltage drops caused by bus line resistance, allowing the use of compact frame designs without requiring excessive frame area to reduce resistance. The system maintains voltage uniformity through active control rather than passive geometric adjustment.
Solution Approach 2:
The patent changes the operating parameters of the bus line by dynamically adjusting the output voltage based on feedback from the bus line voltage monitoring. This allows the system to compensate for resistance effects through parameter adjustment rather than physical redesign.
3Device complexity
If conventional bus line configuration is used, then device complexity is low, but luminance uniformity deteriorates under varying display patterns
Solution Approach 1:
The feedback circuit unit provides active voltage compensation that adapts to varying display patterns and pixel current distributions. This maintains luminance uniformity across different operating conditions without requiring complex passive resistor networks or multiple power supply lines.
Data Source
AI summary
In an organic electroluminescence (EL) display apparatus, a bus line is provided on an edge of a display unit in a display panel. A feedback circuit unit is provided outside of the bus line, and an output voltage of the feedback circuit unit is applied to a connecting part on the bus line. To the feedback circuit unit, a reference voltage from a reference voltage generating unit is applied, a power supply voltage from a power supply unit is supplied, and a monitoring voltage from the connecting part on the bus line is fed back. The feedback circuit unit includes a switching control circuit and a transistor, and controls, using a feedback, the output voltage by supplying or blocking the power supply voltage to an output terminal, so that a voltage at the connecting point is equal to a target voltage determined by the reference voltage.