Switch-Based Power Supply Lines for OLED Brightness Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In active matrix organic electroluminescence display devices, the voltage drop along power supply lines due to resistance components leads to uneven display brightness, particularly when writing data, as the current through multiple pixels connected to the same power supply line reduces the source voltage of driving TFTs, resulting in decreased light emission.
Innovation Solution
Implementing a switch-based power supply system where each row of pixels has a dedicated power supply line connected to either a primary or secondary power supply, allowing for independent voltage control of horizontal power supply lines through a gate driver and selecting circuit, thereby minimizing voltage drops and maintaining consistent brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple pixels share the same power supply line, then device complexity is reduced, but voltage drop occurs leading to uneven display brightness
Solution Approach 1:
The patent divides the power supply system into multiple independent power supply lines, with each horizontal line having its own dedicated power supply. This segmentation eliminates the voltage drop problem caused by shared power lines while maintaining relatively simple device architecture.
Solution Approach 2:
Each horizontal power supply line is provided with independent voltage control through switches connected to different power supply voltages. This allows local adjustment of voltage for each row of pixels, ensuring uniform brightness across the entire display while maintaining low overall device complexity.
2Illumination intensity
If additional transistors are added to compensate for voltage drop, then display brightness uniformity is improved, but aperture ratio decreases and reliability reduces
Solution Approach 1:
The patent introduces switches as intermediary elements between the power supply lines and pixels. These switches enable independent voltage control of each horizontal line without requiring additional transistors within the pixel circuits themselves, thus maintaining aperture ratio and reliability while achieving uniform brightness.
Solution Approach 2:
The power supply voltage for each horizontal line is made dynamically controllable through switches that can select between different power supply voltages. This dynamic control allows compensation for voltage drops and brightness uniformity adjustment without adding static components to the pixel circuits.
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 solution prevents voltage reduction during data writing, ensuring consistent display brightness across the panel without the need for additional transistors, thus maintaining the aperture ratio and reducing the likelihood of failure.
Implementation Method 1
an organic EL element 3 having an anode connected to the drain of the driving TFT 1 and a cathode connected to a low voltage power supply CV... the organic EL element 3 emits light
Data Source
AI summary
An electroluminescent display device having a first and a second power supply; a respective power supply line for each row, wherein each power supply line is placed along a horizontal direction and is connected to the respective first electrodes of the driving TFTs of the pixels in the corresponding row; a plurality of switches, each connected to one or more power supply lines, for selectively connecting the corresponding one or more power supply lines to either the first or the second power supply; a gate driver for selecting a gate line; and a selecting circuit for controlling the plurality of switches, wherein the selecting circuit causes the power supply line corresponding to the selected gate line to be connected to the first power supply, and the one or more power supply lines not corresponding to the selected gate line to be connected to the second power supply.