OLED Demultiplexer Pulse Width Compensation for Luminance Uniformity
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Solution Overview
Problem
Luminance deviation occurs between the first and last pixel row lines of pixel row groups in organic light emitting displays due to the slew rate of data signals, affecting display quality.
Innovation Solution
The organic light emitting display is designed with a data distribution unit that selectively connects data lines to output lines using demultiplexing signals with varying pulse widths, ensuring that the first pixel row group receives a longer data voltage input time to minimize luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If demultiplexers are added to supply data signals to multiple data lines in time division manner, then the number of data driving units is reduced and manufacturing cost is lowered, but luminance deviation occurs between the first and last pixel row lines due to slew rate of data signals
Solution Approach 1:
The pulse width of demultiplexing signals is varied according to the pixel row line number. Specifically, pixel row lines with higher indices (later in the sequence) are assigned longer pulse widths to compensate for the cumulative slew rate effect, ensuring that all pixel rows receive sufficient data voltage transition time regardless of their position in the sequence.
Solution Approach 2:
The patent pre-calculates and assigns different pulse widths to different pixel row lines based on their position in the sequence. This preliminary adjustment of signal parameters compensates for the expected luminance deviation before it occurs, ensuring uniform display quality across all pixel rows.
2Use of energy by moving object
If data signals are supplied sequentially to pixel row groups, then power consumption is reduced and response speed is improved, but luminance deviation occurs between the first and last pixel row lines of pixel row groups
Solution Approach 1:
The pulse width parameter of demultiplexing signals is dynamically adjusted based on the pixel row line index. Later pixel rows receive extended pulse widths to compensate for the time-dependent voltage droop caused by sequential switching, maintaining luminance uniformity while preserving the power-saving sequential drive architecture.
3Ease of operation
If the same pulse width is used for all demultiplexing signals, then the circuit design is simplified and operation is easier, but luminance deviation becomes visually recognizable and display quality is reduced
Solution Approach 1:
Different pulse widths are assigned to different pixel row lines based on their specific position in the sequence. This localized customization of signal parameters ensures that each pixel row receives the appropriate amount of time for voltage stabilization, compensating for position-dependent luminance variations while maintaining overall system functionality.
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 approach effectively reduces luminance deviation between pixel row groups, enhancing display quality by optimizing the timing of data voltage distribution across the display.
Implementation Method 1
The organic light emitting display displays an image using the organic light emitting diodes that generate light through recombination of electrons and holes
Data Source
AI summary
An organic light emitting display that defines a plurality of pixels arranged in a matrix form as a plurality of pixel row groups, each of which includes the same number of pixel rows and individually drives the respective pixel row groups. The organic light emitting display includes a display unit including the plurality of pixels, a plurality of data lines, and a plurality of scan lines: a scan driving unit configured to apply scan signals to the plurality of pixels; a data driving unit configured to apply data voltages that are provided to the plurality of pixels to a first output line; and a data distribution unit configured to selectively connect at least two data lines that are continuously arranged to the first output line according to demultiplexing signals. The demultiplexing signals that correspond to the pixel rows included in the respective pixel row groups have different pulse widths.