Row Power Line Segmentation for OLED Voltage Uniformity
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Solution Overview
Problem
Conventional active matrix organic EL display apparatuses suffer from voltage fluctuation issues due to increased wiring resistance in power lines, leading to crosstalk and uneven luminance across pixels, causing user discomfort.
Innovation Solution
The apparatus connects multiple first power lines across rows via a third power line using second switching transistors, allowing for reduced voltage drop differences and independent voltage control for each row, thereby curbing crosstalk and ensuring uniform power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple first power lines are connected via a third power line using second switching transistors, then voltage drop differences are reduced and crosstalk is curbed, but device complexity increases due to additional power lines and switching transistors
Solution Approach 1:
The power supply system is segmented into multiple first power lines (one per row) and a third power line that connects them. Second switching transistors are placed at intersections to selectively connect or disconnect segments. This segmentation allows independent voltage control for each row while providing a path for voltage equalization through the third power line, resolving the contradiction between uniformity and complexity.
Solution Approach 2:
The system dynamically connects or disconnects the third power line to first power lines using second switching transistors controlled by control lines. During normal operation, the switching transistors are off to maintain independent row control. During compensation periods, they are turned on to equalize voltages. This dynamic switching resolves the contradiction by providing uniformity only when needed without permanently increasing complexity.
2Adaptability or versatility
If independent voltage control is implemented for each row using first power lines, then power supply flexibility is improved, but voltage fluctuations and crosstalk increase due to wiring resistance
Solution Approach 1:
The third power line acts as an intermediary that connects all first power lines together. When second switching transistors are activated, this intermediary path allows voltage to equalize across rows, compensating for voltage drops caused by wiring resistance. This resolves the contradiction by maintaining independent control capability while adding a mediation mechanism to stabilize voltages.
Solution Approach 2:
The system uses control lines to monitor and control the state of second switching transistors based on detected voltage variations. When voltage fluctuations are detected in a row, the control system activates the corresponding switching transistors to connect to the third power line, creating a feedback loop that stabilizes voltage. This resolves the contradiction between independent control and voltage stability.
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 effectively reduces voltage fluctuations and crosstalk, maintaining consistent luminance across pixels and enhancing the display quality by minimizing the impact of power supply voltage variations.
Implementation Method 1
An organic EL element used in an organic EL display apparatus is different from a liquid-crystal cell which is controlled by a voltage applied to the liquid-crystal cell in that luminance of each luminescence element is controlled by a value of a current flowing through the luminescence element
Data Source
AI summary
An image display apparatus according to an implementation of the present invention includes: pixel circuits disposed in rows and columns; first power lines and control lines disposed in respective rows; a third power line; second switching transistors disposed at least one for each of the rows and each having a gate terminal connected to the control line disposed in the corresponding row, one of a source terminal and a drain terminal connected to the first power line disposed in the corresponding row, and the other of the source terminal and the drain terminal connected to the third power line; and a power supply unit which supplies the same voltage to the first power lines and the third power line when the second switching transistors are turned ON.