Organic EL Display Voltage Control for Brightness Sticking
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Solution Overview
Problem
Organic EL display devices face issues with brightness uniformity, leading to 'sticking' phenomena when displaying images with varying brightness patterns, as existing techniques can emphasize brightness differences and cause display quality degradation.
Innovation Solution
A display device with a common second electrode that divides the display area into regions, using differential amplifiers to compare brightness information and adjust referential voltages accordingly to maintain uniform brightness across the screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common second electrode is used for the entire display area, then the device structure is simple and easy to manufacture, but brightness uniformity deteriorates and sticking phenomena occur in areas with varying brightness patterns
Solution Approach 1:
The common second electrode is divided into multiple independent electrode regions corresponding to different display areas. Each electrode region can be independently controlled with separate referential voltages, allowing brightness compensation in specific areas without affecting the entire display. This segmentation resolves the contradiction by maintaining structural simplicity while enabling localized brightness control to prevent sticking phenomena.
Solution Approach 2:
Different referential voltages are applied to different electrode regions based on local brightness requirements. Areas prone to sticking receive adjusted voltages to compensate for brightness variations, while other areas maintain normal operation. This local quality approach allows the system to address brightness uniformity issues in specific regions without complicating the overall electrode structure.
2Reliability
If the display brightness is lowered to prevent sticking, then sticking phenomena are reduced, but the overall display quality and brightness are degraded
Solution Approach 1:
Instead of uniformly lowering brightness across the entire display, the invention applies adjusted referential voltages only to specific electrode regions where sticking is likely to occur. This allows maintaining high overall display brightness while preventing sticking in localized areas through targeted voltage control.
Solution Approach 2:
The system monitors brightness patterns and automatically adjusts referential voltages to areas where sticking is detected or predicted. This feedback mechanism prevents sticking phenomena without requiring global brightness reduction, thereby maintaining display quality while preventing degradation.
3Device complexity
If the screen brightness is uniformly controlled, then the control mechanism is simple, but brightness variations in different display areas cannot be compensated
Solution Approach 1:
The control mechanism is segmented into multiple independent control channels, each managing a specific electrode region. While this increases control complexity compared to uniform control, the segmentation allows precise brightness compensation in each region, resolving the contradiction by enabling area-specific brightness management.
Solution Approach 2:
The control system applies different referential voltages to different electrode regions based on local brightness characteristics. This local quality control compensates for brightness variations in specific areas while maintaining relatively simple control logic for each region, balancing complexity and effectiveness.
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
The solution effectively reduces the likelihood of brightness sticking by dynamically adjusting voltages based on brightness differences, ensuring consistent display quality across the screen.
Implementation Method 1
in an organic EL (electroluminescence) display device, by allowing an electric current to independently flow into organic EL elements provided to respective pixels, the organic EL elements are made to respectively emit light
Implementation Method 2
uses differential amplifiers to compare brightness information and adjust referential voltages accordingly
Data Source
AI summary
The present invention provides a display device which can obviate the possibility of sticking as a whole of a display area even when the brightness is relatively changed on a display area. In a display device, a plurality of pixels are arranged in the inside of a display area and the respective pixels include electrodes to which signals are independently inputted and a common second electrode to which a reference signal with respect to the signals is inputted, the current from the cathode electrode in the first and second display areas are respectively measured, and when the electric current of the first display area is larger than the electric current of the second display area, a potential difference between the cathode electrode of the first display area and the anode electrode of the first display area is made small.