Segmented Power Wiring for Active Matrix EL Display Voltage Drop
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Solution Overview
Problem
Conventional active matrix EL displays experience poor image quality due to voltage drops on power supply wiring, leading to brightness inconsistencies and smear, especially in larger devices with longer wiring lengths.
Innovation Solution
The implementation of a matrix arrangement of pixel circuits with separate wirings for image signals and power, where both wirings receive power during image display, reducing voltage drops and maintaining consistent brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power supply line is used to supply power to all pixel circuits, then the device complexity is reduced, but voltage drops occur causing brightness inconsistencies and poor image quality
Solution Approach 1:
The power supply system is segmented into multiple parallel power supply lines (first power supply line and second power supply line) that independently supply power to different sets of pixel circuits. This segmentation reduces the current load on each individual line, minimizing voltage drops and ensuring uniform brightness across the display without significantly increasing overall system complexity.
Solution Approach 2:
Different regions of the display are supplied by different power supply lines configured to compensate for local voltage drops. The first power supply line serves certain columns while the second serves other columns, with each line optimized for its specific region to maintain consistent power delivery and brightness uniformity across the entire display area.
2Area of stationary object
If longer wiring is used to cover larger display areas, then the display size is increased, but voltage drops increase causing smear and poor image quality
Solution Approach 1:
The display area is divided into multiple regions served by different power supply lines. Each power supply line has a limited length serving a specific column or set of columns, preventing any single line from becoming excessively long. This segmentation allows the display to cover large areas while maintaining short individual wiring lengths to minimize voltage drops and prevent smear.
Solution Approach 2:
The power supply network is extended into multiple dimensions by creating parallel power supply lines that serve different column groups. Instead of using a single long horizontal line, the system uses multiple shorter lines arranged in parallel, effectively distributing power across the large display area while keeping individual line lengths manageable and voltage drops minimal.
3Illumination intensity
If high current is supplied to light EL elements, then the brightness is increased, but voltage drops on power supply lines increase causing brightness inconsistencies
Solution Approach 1:
The total current required for lighting is segmented and distributed across multiple parallel power supply lines. Each line carries a portion of the total current to its assigned pixel circuits, reducing the current load on any single line. This allows high overall brightness to be achieved while maintaining low individual line currents to minimize voltage drops and ensure brightness uniformity.
Solution Approach 2:
Each power supply line is configured with appropriate current capacity and wiring dimensions suited to its specific load requirements. Lines serving different column groups are optimized for their local current demands, ensuring that each region receives sufficient current for high brightness while maintaining voltage stability and uniformity across the entire display.
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 minimizes the impact of voltage drops on the brightness of EL elements, significantly reducing the occurrence of poor image quality issues like smear and enabling high-quality image display, especially in larger devices.
Implementation Method 1
an EL element 25 and a circuit element for controlling the light-emission intensity of the EL element
Data Source
AI summary
Improvement is to be achieved against poor image quality attributable to voltage drops on wirings, and the image quality especially of large image display devices is to be ameliorated. The circuit configuration comprises a scanning circuit for controlling a plurality of pixel circuits; a plurality of scanning wirings for conveying the signals of the scanning circuit to the pixel circuits; a plurality of first and second wirings for supplying image signals and power to the pixel circuits, arranged in parallel to each other and crossing said scanning wirings; and a drive circuit for supplying image signals and power to the first and second wirings; all disposed over a glass substrate, wherein the drive circuit supplies power to both first and second wirings when the light-emitting devices emit light in response to image signals.