Demultiplexer Controller for OLED Luminance Uniformity
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Solution Overview
Problem
Existing organic light emitting displays face challenges in maintaining uniform luminance across sub-pixels due to differences in charging times, leading to potential defects like blurry shapes and unequal image display.
Innovation Solution
The implementation of a demultiplexer controller that supplies initialization voltage and data signals to sub-pixels in a time-divisional manner, with specific periods for green, red, and blue sub-pixels, using switches to control data lines and ensure concurrent signal supply to green and red sub-pixels during different periods, thereby optimizing charging times and reducing luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If data signals are supplied to all sub-pixels simultaneously, then display quality should be uniform, but the device complexity increases due to additional demultiplexer components
Solution Approach 1:
The patent segments the data signal supply process into different time periods for different sub-pixel groups. The demultiplexer divides the data lines into multiple groups (first data lines, second data lines, third data lines) and supplies data signals to each group in sequential time periods within one horizontal period, rather than simultaneously to all sub-pixels. This time-divisional approach maintains display quality while managing device complexity through structured signal distribution.
Solution Approach 2:
The patent implements periodic action by dividing the horizontal period into multiple time periods, with each time period dedicated to supplying data signals to specific sub-pixel groups. The demultiplexer controller orchestrates this periodic supply pattern, ensuring that green sub-pixels receive signals in one time period, red sub-pixels in another, and blue sub-pixels in a third time period, thereby achieving uniform display quality through structured temporal distribution.
2Device complexity
If different data signals are supplied to different sub-pixels at different times, then device complexity is reduced, but luminance uniformity deteriorates due to unequal charging times
Solution Approach 1:
The patent applies local quality by providing different initialization voltages to different sub-pixel groups based on their specific charging characteristics. The demultiplexer supplies a first initialization voltage to green sub-pixels, a second initialization voltage to red sub-pixels, and a third initialization voltage to blue sub-pixels, tailored to each group's requirements. This localized approach ensures that each sub-pixel group achieves uniform luminance despite receiving signals at different times.
Solution Approach 2:
The patent changes the voltage parameter dynamically by supplying different initialization voltages to different sub-pixel groups during different time periods. The demultiplexer controller adjusts the voltage levels according to the specific charging characteristics of each sub-pixel group, ensuring that all sub-pixels reach their operating points simultaneously, thereby maintaining luminance uniformity while using time-divisional signal supply.
3Loss of time
If initialization voltage is supplied to all data lines simultaneously, then charging time is reduced, but the device complexity increases due to additional control circuits
Solution Approach 1:
The patent makes the demultiplexer a multi-functional device that performs both data signal distribution and initialization voltage supply functions. The same demultiplexer structure that divides data lines into groups for sequential data signal supply also handles the initialization voltage distribution, eliminating the need for separate control circuits and reducing overall device complexity while maintaining efficient charging times.
Data Source
AI summary
An organic light emitting display includes first sub-pixels, second sub-pixels and third sub-pixels at an area defined by scan lines and data lines; a data driver configured to supply an initialization voltage and data signals to output lines; demultiplexers coupled to respective ones of the output lines, each demultiplexer being configured to supply a plurality of the data signals to a plurality of the data lines; and a demultiplexer controller configured to control the demultiplexer so that data signals are concurrently supplied to at least one of the first sub-pixels, the second sub-pixels or the third sub-pixels.