Alternating Video Signal Input for OLED Luminance Uniformity
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Solution Overview
Problem
Existing organic electroluminescence (EL) display devices face challenges in achieving uniform luminance and high frame rates due to variations in threshold voltage and mobility of driving transistors, leading to luminance unevenness and visual streaks across the screen, especially when increasing panel size and enhancing frame rate.
Innovation Solution
The implementation of a Simultaneous Threshold Correction (STC) driving system, where multiple horizontal lines are grouped into units for simultaneous threshold correction, and the order of video signal voltage input is alternated between units to synchronize light emission, ensuring consistent luminance across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If simultaneous threshold correction is applied to multiple horizontal lines grouped into units, then the threshold correction period is extended and luminance uniformity is improved, but the device complexity increases due to the need for writing scanners and signal selectors to coordinate alternating input orders
Solution Approach 1:
The pixel array is divided into multiple units, each unit containing multiple horizontal lines. This segmentation allows independent control and alternating input sequences for different units, enabling simultaneous threshold correction while maintaining luminance uniformity across the entire display.
Solution Approach 2:
The writing scanner and signal selector are configured to pre-coordinate the alternating input order of video signals for different units before simultaneous threshold correction is applied. This preliminary arrangement of input sequences prevents luminance differences from occurring in the first place.
2Manufacturing precision
If the writing scanner inputs video signals in alternating order for different units, then visual streaks are eliminated and display quality is enhanced, but the productivity is reduced due to the complex scanning sequence requirements
Solution Approach 1:
The writing scanner implements periodic alternating input sequences for different units, switching between normal order and reverse order in a regular pattern. This periodic action eliminates visual streaks by ensuring that adjacent units do not display simultaneously corrected lines in the same sequence, preventing synchronized luminance variations.
3Speed
If multiple horizontal lines are grouped into units for simultaneous correction, then the frame rate is enhanced and response speed is improved, but the loss of time increases due to the coordination overhead for alternating signal input
Solution Approach 1:
Multiple horizontal lines within each unit are combined for simultaneous threshold correction, allowing parallel processing of multiple lines at once. This merging approach accelerates the correction process and improves response speed, while the alternating input sequence across units minimizes coordination overhead by operating in a predictable periodic pattern.
Data Source
AI summary
Disclosed herein is a display device including a pixel array configured to include pixel circuits arranged in a matrix having a light emitting element, driving transistor, sampling transistor, and hold capacitor. The display device further includes a signal selector, driving control scanner, and writing scanner. The signal selector alternately carries out supply of a video signal voltage in order from a beginning line to an end line in a unit and supply of a video signal voltage in order from an end line to a beginning line in a unit. The writing scanner outputs the pulse to the writing control lines in such a way that input of a video signal voltage in order from a beginning line to an end line in a unit and input of a video signal voltage in order from an end line to a beginning line in a unit are alternately carried out.