Double Bar Scrolling for Active Matrix Electroluminescent Displays
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Solution Overview
Problem
Active matrix electroluminescent display devices face issues with motion blur due to continuous pixel illumination, leading to reduced duty cycle solutions like flashing, which can introduce field flicker and voltage drop problems, especially in large displays.
Innovation Solution
Implementing a double bar scrolling method where two bands of rows are illuminated, scrolling in the column direction, with a duty cycle of less than 75% to reduce peak brightness and increase effective duty cycle, allowing for improved motion perception and reduced voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If continuous pixel illumination is used in active matrix electroluminescent display devices, then the display provides continuous light output, but motion blur occurs due to eye-tracking motion and light integration
Solution Approach 1:
The patent implements periodic illumination by dividing the frame period into multiple sub-intervals where different bands of rows are illuminated sequentially. Instead of continuous illumination, the display uses pulsed illumination patterns with duty cycles less than 75%, creating distinct on/off periods that reduce motion blur while maintaining acceptable brightness through temporal integration.
Solution Approach 2:
The patent segments the display into multiple bands of rows that are illuminated in different time intervals within each frame period. This segmentation allows different portions of the display to be activated at different times, reducing the overall duty cycle and preventing motion blur while maintaining continuous visual output through persistence of vision.
2Manufacturing precision
If the duty cycle is reduced to reduce motion blur, then image sharpness improves, but peak brightness increases and field flicker occurs
Solution Approach 1:
The display is divided into multiple bands of rows that are illuminated in different time intervals. By distributing the illumination across multiple segments rather than illuminating all rows simultaneously, the peak brightness requirement for any single time interval is reduced while maintaining the same average luminance through temporal distribution.
Solution Approach 2:
The patent uses periodic illumination patterns with multiple sub-intervals per frame period. This distributes the total light output requirement across multiple periods, reducing peak brightness demands while maintaining acceptable average luminance and reducing motion blur through the periodic on/off cycling.
3Manufacturing precision
If flashing techniques are used to reduce duty cycle, then motion blur is reduced, but voltage drops increase especially in large displays
Solution Approach 1:
By segmenting the display into multiple bands activated at different times, the total current draw at any given moment is reduced compared to full-screen flashing. This temporal distribution of power consumption reduces voltage drops across power lines while achieving the same duty cycle reduction and motion blur improvement.
Solution Approach 2:
The periodic activation pattern with duty cycles less than 75% reduces the average current draw compared to continuous or full-frame flashing. This reduces the overall power consumption and minimizes voltage drops across power distribution lines while maintaining image sharpness through reduced motion blur.
4Manufacturing precision
If the whole display is flashed simultaneously, then duty cycle is reduced and motion blur is minimized, but large area flicker is introduced
Solution Approach 1:
The patent divides the display into multiple bands of rows that are illuminated in different time intervals within each frame period. This segmentation distributes the flicker effect across different spatial regions and time intervals, reducing the perception of large-area uniform flicker while maintaining the duty cycle reduction needed for sharp motion rendering.
Solution Approach 2:
By using multiple periodic illumination sub-intervals with different timing for different bands, the patent creates a more complex temporal pattern that reduces the perception of uniform field flicker. The staggered activation of different bands creates a smoother overall visual transition compared to simultaneous flashing of 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
The double bar scrolling method enhances image sharpness by maintaining short illumination periods, reduces large area flicker, and minimizes voltage drops across power lines, improving the overall performance of active matrix OLED displays.
Implementation Method 1
organic light emitting diode, represented here as a diode element (LED) and comprising a pair of electrodes between which one or more active layers of organic electroluminescent material is sandwiched
Data Source
AI summary
In an active matrix electroluminescent display, a plurality of rows of pixels are illuminated, defining at least two bands of rows separated by a non-illuminated band. The bands of rows of pixels scroll in the column direction over time, and at most 75% of the rows are illuminated at any point in time. This method is in essence a double bar scrolling method. By scrolling two bars, the required peak brightness is reduced as the effective overall duty cycle is increased. However, the period of illumination can still remain short, so that motion perception remains improved. The scrolling speed can be halved for the same frame rate or else the frame rate can be increased to reduce flicker.