OLED Demultiplexer Pre-Charging for Brightness Uniformity
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Solution Overview
Problem
Current organic electroluminescent displays with active matrix type pixel circuits face challenges in uniform brightness due to non-uniform threshold voltages and require extensive time for data programming, especially with the passive matrix type's high power consumption and short drive time.
Innovation Solution
The implementation of a current programming type pixel circuit with a demultiplexer between the data driver and the organic electroluminescent display panel, which includes a plurality of demultiplexing circuits and control signal lines to alternately select output data lines and apply pre-charging voltage, thereby simplifying the data driver structure and reducing data programming time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a current programming type pixel circuit is used, then brightness uniformity is improved, but data programming time is increased
Solution Approach 1:
The demultiplexer applies pre-charging voltage to the output data line before transmitting the data current signal. This preliminary action prepares the output line by establishing a baseline voltage level, which reduces the time required for the current programming type pixel circuit to achieve stable brightness, thereby resolving the contradiction between brightness uniformity and data programming time.
2Device complexity
If passive matrix type is used, then structure is simplified, but power consumption is increased and drive time is shortened
Solution Approach 1:
The demultiplexer serves as an intermediary device between the data driver and the pixel circuits. It receives data current signals from the data driver, applies pre-charging voltage to the output data lines, and then transmits the signals to the pixel circuits. This intermediary function enables the system to achieve active matrix type performance with simplified passive matrix structure, resolving the contradiction between structure simplicity and power consumption.
3Use of energy by moving object
If active matrix type is used, then power consumption is reduced and drive time is increased, but structure becomes complicated
Solution Approach 1:
The system is segmented into distinct functional modules: the data driver that generates data current signals, the demultiplexer that processes and pre-charges output data lines, and the pixel circuits that display images. This segmentation allows the passive matrix structure to achieve active matrix type power efficiency by clearly separating the functions of data generation, signal conditioning, and display output, thereby resolving the contradiction between structure complexity and power consumption.
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 solution ensures uniform brightness across the screen by isolating the pixel circuit from threshold voltage variations and significantly reduces the time needed for data programming by pre-charging the output data lines before transmitting the input data current.
Implementation Method 1
An organic electroluminescent display is based on a phenomenon that an exciton emits light of a specific wavelength in an organic thin film, wherein the exciton is formed by recombination of an electron and a hole respectively injected from a cathode and an anode
Data Source
AI summary
An organic electroluminescent display and a demultiplexer, wherein the organic electroluminescent display comprising: a plurality of pixels displaying an image corresponding to output data current; a plurality of scan lines to transmit a scan signal to the plurality of pixels; a plurality of output data lines to transmit the output 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 demultiplexing circuit; and a data driver outputting input data current to the demultiplexer, wherein the demultiplexing circuit transmits the input data current after applying pre-charging voltage to the output data line selected among the output data lines in sequence. With this configuration, the present invention provides an organic electroluminescent display and a demultiplexer, in which comprises a current programming type pixel circuit uniformizing brightness of a screen even if threshold voltage is not uniform, and the demultiplexer placed between a data driver and an organic electroluminescent display panel, thereby reducing time taken to program data of a current programming type pixel.