Capacitive Load Units for Display Luminance Uniformity
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Solution Overview
Problem
Organic EL display devices experience luminance differences due to variations in wiring capacitance and resistance, leading to irregularities in display uniformity, particularly between central and peripheral light-emitting elements and those near data line terminations.
Innovation Solution
Incorporating capacitive load units between scanning lines and scanning circuits, and in data line terminations, to stabilize scanning signals and reduce luminance variations by equalizing wiring capacitance and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If scanning lines are extended to drive light-emitting elements in the central portion, then coverage area is improved, but wiring capacitance and resistance increase causing luminance differences
Solution Approach 1:
The patent applies local quality by introducing capacitive load units at specific locations (between scanning lines and scanning circuits, and at data line terminations) rather than uniformly throughout the entire display device. This localized approach compensates for wiring capacitance and resistance effects in specific regions without adding unnecessary components throughout the entire device, thereby improving luminance uniformity while maintaining coverage area.
Solution Approach 2:
The capacitive load units act as intermediary elements between the scanning lines/scanning circuits and the light-emitting elements. These intermediary components compensate for the harmful effects of wiring capacitance and resistance by providing additional capacitive loading that equalizes the time constants across different regions of the display, thereby mediating the signal distortion and improving overall luminance uniformity.
2Area of stationary object
If data lines are extended to reach all light-emitting elements, then coverage is improved, but parasitic capacitance varies causing luminance irregularities
Solution Approach 1:
The patent applies local quality by placing capacitive load units specifically at data line terminations and between scanning lines and scanning circuits, rather than uniformly distributing components throughout the display. This targeted approach compensates for parasitic capacitance variations in specific regions where data lines are longest and have highest parasitic capacitance, thereby improving luminance uniformity without affecting overall coverage.
Solution Approach 2:
The capacitive load units at data line terminations serve as intermediary components that compensate for parasitic capacitance effects. By providing additional capacitive loading at the termination points, these intermediaries equalize the time constants across different data line lengths and positions, mediating the signal distortion caused by varying parasitic capacitance and improving luminance uniformity.
3Manufacturing precision
If capacitive load units are added to equalize wiring capacitance, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The patent minimizes device complexity by placing capacitive load units only at specific critical locations (between scanning lines and scanning circuits, and at data line terminations) rather than throughout the entire display device. This localized approach provides effective compensation for wiring capacitance and parasitic capacitance while adding minimal additional components, thereby improving luminance uniformity with minimal increase in device complexity.
Solution Approach 2:
The capacitive load units function as simple intermediary components that provide effective compensation with minimal circuit complexity. These units consist essentially of capacitive elements that can be integrated into existing wiring structures, providing luminance uniformity improvement without requiring complex control circuits or additional active components, thus achieving the goal with minimal added complexity.
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 enhances display uniformity by minimizing luminance differences and reducing shading or irregularities, resulting in a more consistent and uniform display output.
Implementation Method 1
a capacitive load unit provided between a scanning line and a scanning circuit, and a capacitive load unit provided in a data line
Data Source
AI summary
A display device includes: (A) scanning circuits; (B) a video signal output circuit; (C) a current supply unit; (D) M current supply lines connected to the current supply unit and extending in a first direction; (E) M scanning lines connected to the scanning circuits and extending in the first direction; (F) N data lines connected to the video signal output circuit and extending in a second direction; and (G) N×M light-emitting elements in total of N light-emitting elements in the first direction and M light-emitting elements in the second direction different from the first direction arranged in a two-dimensional matrix, each light-emitting element having a light-emitting unit and a driving circuit for driving the light-emitting unit. The driving circuit of each light-emitting element is connected to the corresponding current supply, scanning, and data lines. A capacitive load unit is provided between each scanning line and each scanning circuit.