OLED Driving Circuit Uniform Discharge for Gray Scale Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional organic light emitting display devices face issues with displaying images with correct brightness due to threshold voltages of driving transistors in pixels, which affect the accuracy of gray scales and overall image quality.
Innovation Solution
The organic light emitting display device employs a data driver that generates PWM signals and sinks uniform reference current to discharge gate electrodes of driving transistors at a uniform speed, controlling current flow through OLEDs to ensure accurate gray scale representation, independent of the threshold voltages of the driving transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional driving methods are used, then the device structure is simple, but the gray scale accuracy and image quality deteriorate due to threshold voltage variations
Solution Approach 1:
The patent applies preliminary action by pre-charging the gate electrode to a reference voltage before the emission period, then systematically discharging it during a dedicated discharge period. This pre-positioning of the gate voltage enables precise control of the OLED current and gray scale, resolving the issue of inaccurate gray scale representation caused by threshold voltage variations without requiring complex real-time compensation circuits.
Solution Approach 2:
The patent changes the operational parameters by introducing a multi-period driving scheme where the gate electrode voltage is dynamically adjusted through controlled charging and discharging phases. By varying the discharge current and duration in the discharge period, the system achieves precise gray scale control independent of transistor threshold voltage, thereby improving manufacturing precision without excessive complexity.
2Manufacturing precision
If threshold voltage compensation is implemented, then gray scale accuracy improves, but the circuit complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements self-service by using the driving transistor itself as the compensation element. The gate electrode is charged to a reference voltage and then discharged through a controlled process that inherently compensates for threshold voltage variations. This eliminates the need for separate compensation circuits or additional transistors, maintaining ease of manufacture while achieving high gray scale accuracy.
Solution Approach 2:
The patent extracts the compensation function from complex compensation circuits and integrates it into the basic driving transistor operation. By separating the charging phase (setting reference voltage) and discharging phase (controlling gray scale), the system achieves threshold voltage compensation using only the essential driving transistor and capacitor, simplifying manufacturing while improving precision.
3Manufacturing precision
If multi-period driving scheme is used, then image quality and gray scale accuracy improve, but the driving complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the driving cycle into distinct periods: a first period for charging the gate electrode to reference voltage, a second period with sub-phases for discharge, and a third period for emission. This temporal segmentation of the driving waveform enables precise gray scale control through systematic voltage discharge, improving image quality while managing driving complexity through structured timing control.
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 allows for the display of images with correct brightness and accurate gray scales, regardless of the threshold voltages of the driving transistors, thereby improving the overall image quality and consistency.
Implementation Method 1
organic light emitting diodes (OLED) that generate light by re-combination of electrons and holes
Data Source
AI summary
There is provided an organic light emitting display device and a method of driving the same. The organic light emitting display device includes pixels, a data driver, a scan driver to sequentially supply scan signals to scan lines, and a control line driver configured to supply emission control signals to emission control line. The data driver is to discharge the gate electrodes of the driving transistors of the pixels at a uniform discharge speed in a third period within a second period, wherein the second period is after the first period, the third period corresponds to a light emitting gray scale of each pixel, and after the second period, the pixels emit light.