Driving Current Output Apparatus for OLED Uniformity
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Solution Overview
Problem
Organic light emitting displays face issues with non-uniform driving currents due to operation characteristics of electric elements and variations in supply voltage, leading to decreased image quality.
Innovation Solution
A driving current output apparatus with a bias current outputting unit and a driving current outputting unit, connected via switches and transistors, ensures that the magnitude of the driving current is substantially the same as the bias current, using a circuit configuration that includes transistors, capacitors, and switches to synchronize and regulate the current output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional driving current generator is used, then device complexity is reduced, but driving current uniformity deteriorates due to transistor variations and supply voltage fluctuations
Solution Approach 1:
The driving current generator is divided into multiple independent driving current output circuits, each capable of generating uniform driving current. By segmenting the system, each circuit can be independently optimized and controlled, ensuring current uniformity while managing overall complexity through modular design.
Solution Approach 2:
A bias current outputting unit is introduced as an intermediary component that provides a stable reference current to the driving current output circuits. This bias current serves as a mediator that compensates for variations in supply voltage and transistor parameters, ensuring uniform driving current output without requiring complex control mechanisms in each circuit.
2Manufacturing precision
If multiple driving current output circuits are used, then current uniformity is improved, but switch synchronization complexity increases
Solution Approach 1:
Multiple driving current output circuits are merged into a unified system controlled by a single bias current outputting unit. The switches in each circuit are synchronized through common control signals, reducing the complexity of detecting and measuring synchronization status while maintaining current uniformity across all outputs.
3Reliability
If transistor variations are not compensated, then device complexity is minimized, but image quality deteriorates due to non-uniform driving currents
Solution Approach 1:
The bias current outputting unit provides a feedback mechanism that compensates for transistor variations and supply voltage fluctuations. By using the bias current as a reference, the system automatically adjusts to maintain uniform driving current output, improving image quality without requiring complex active compensation circuits in each driving current output unit.
Data Source
AI summary
A display device, which includes a plurality of pixels; a data driver for outputting data signals to the pixels; a bias current outputting unit for outputting a bias current having a predetermined magnitude; a plurality of driving current outputting units for outputting driving currents to the pixels; and a first switch connected between the bias current outputting unit and the driving current outputting units for selecting one of the driving current outputting units to connect to the bias current outputting unit, wherein the magnitudes of the driving currents are substantially the same as a magnitude of the bias current.