OLED Demultiplexer Pre-Charge Circuit for Data Programming Speed
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Solution Overview
Problem
In organic electroluminescent displays, the current programming method faces challenges with data programming speed, especially in low gradation, due to the influence of voltage state charged to parasitic capacitance of data lines, leading to increased production costs and complex data driver structures.
Innovation Solution
A demultiplexer with sample/hold circuits and pre-charge switches is introduced, which demultiplexes and transmits pre-charge voltage to data lines before data current, reducing the time required for data programming and simplifying the data driver structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current programming method is used to drive organic electroluminescent displays, then the display can be operated with simple structure, but the data programming speed decreases due to voltage state charged to parasitic capacitance of data lines
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charge switch that charges the data line to a predetermined voltage level before data current is programmed. This pre-charging action prepares the data line in advance, eliminating the slow charging effect caused by parasitic capacitance and enabling faster data programming speed without increasing driver complexity.
2Device complexity
If the passive matrix method is used to drive organic electroluminescent displays, then the structure remains simple and implementation is easy, but energy consumption increases and driving time decreases for large screens
Solution Approach 1:
The patent applies segmentation by dividing the data driver into multiple independent data line drivers, each capable of autonomous operation with its own pre-charge switch. This segmentation allows each data line to be independently optimized and charged, reducing overall energy consumption compared to passive matrix methods while maintaining simple display structure.
3Device complexity
If the passive matrix method is used to drive organic electroluminescent displays, then the structure remains simple, but the driving time for each emissive element decreases in large screen implementations
Solution Approach 1:
The pre-charge switch charges data lines to a predetermined voltage level before data current is programmed, eliminating the slow charging effect caused by parasitic capacitance. This preliminary action significantly reduces the data programming time for each emissive element, enabling faster driving times while maintaining simple display structure.
4Speed
If pre-charge voltage is transmitted to data lines before data current, then data programming speed increases, but the device complexity increases due to additional pre-charge switches and circuits
Solution Approach 1:
The patent merges the pre-charge function with the existing data driver architecture by integrating pre-charge switches into the data line driver circuitry. This combining approach enables faster data programming speed while minimizing the increase in device complexity through shared circuit elements and coordinated control signals.
Data Source
AI summary
An organic electroluminescent display and a demultiplexer, wherein the organic electroluminescent display comprises: a plurality of pixels including a plurality of sub-pixels and displaying images corresponding to a first data current; a plurality of scan lines transmitting a scan signal to the plurality of pixels; a plurality of first data lines transmitting the first data current to the plurality of pixels; a scan driver outputting the scan signal to the plurality of scan lines; a demultiplexer comprising a plurality of sample-and-hold demultiplexing circuits; and a data driver outputting a second data current to a plurality of second data lines, wherein the demultiplexing circuit transmits the first data current, obtained by demultiplexing the second data current in sample/hold method, to the first data lines, wherein a pre-charge voltage corresponding to the second data current is previously transmitted to the first data lines before the first data current is transmitted to the first data lines.