OLED Display Driving Circuit with Periodic Anode Reset
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Solution Overview
Problem
Organic light emitting devices face issues with blurring due to mismatched eye motion and screen motion, and uncontrollable luminance caused by changing TFT threshold voltage and non-uniform semiconductor properties, leading to power consumption and drive complexity increases.
Innovation Solution
A display device with pixels driven by a control circuit generating specific signals to control switching transistors and capacitors, allowing for controllable anode voltage and luminance, using p-channel and n-channel electric field effect transistors to manage voltage and current efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fixed image is displayed for a predetermined time within one frame using impulse drive method, then the blurring is reduced, but the luminance of the image decreases
Solution Approach 1:
The patent applies periodic action by using impulse drive method where the fixed image is displayed for a predetermined time within one frame and black is displayed for the rest of the frame. This periodic display approach reduces blurring by limiting the display time at fixed positions while managing luminance through controlled timing cycles.
2Illumination intensity
If the image luminance is increased while the image is displayed, then the luminance is improved, but the power consumption increases
Solution Approach 1:
The patent uses periodic action with impulse drive method where the image is displayed for a predetermined time within one frame and black is displayed for the rest of the frame. This approach manages the trade-off between luminance and power consumption by controlling the display time and using controlled timing cycles to maintain acceptable luminance while reducing overall power consumption compared to continuous display.
3Device complexity
If the TFT threshold voltage changes with time, then the device operation is simplified, but the desired luminance generation is impeded
Solution Approach 1:
The patent introduces feedback by including a sensing transistor connected to the light-emitting device and a compensation capacitor. The sensing transistor detects changes in the driving transistor's threshold voltage over time, and this information is stored in the compensation capacitor to compensate for the threshold voltage drift, thereby maintaining stable luminance output despite TFT aging effects.
Solution Approach 2:
The patent uses a compensation capacitor as an intermediary element that stores the threshold voltage information detected by the sensing transistor. This capacitor acts as a mediator between the driving transistor and the light-emitting device, compensating for threshold voltage changes and ensuring stable luminance generation without increasing overall drive complexity.
4Device complexity
If the voltage at the anode of the organic light emitting element uncontrollably changes, then the device structure is simplified, but the current flowing to the light emitting element uncontrollably changes affecting displayed luminance
Solution Approach 1:
The patent implements feedback control by using a sensing transistor connected to the light-emitting device to detect voltage changes at the anode. This sensing mechanism provides information about uncontrollable voltage variations, allowing the control circuit to compensate and maintain stable current flow and luminance output without significantly increasing device complexity.
Solution Approach 2:
The sensing transistor serves as an intermediary element that monitors the voltage at the anode of the light-emitting device. By detecting these voltage changes, the sensing transistor enables the control circuit to maintain stable current control and luminance output despite uncontrollable voltage variations, acting as a buffer between the voltage source and the light-emitting element.
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
The solution provides improved luminance control and reduced blurring by managing voltage and current effectively, enhancing display quality while minimizing power consumption and drive complexity.
Implementation Method 1
a light-emitting device
Implementation Method 2
p-channel and n-channel electric field effect transistors to manage voltage and current efficiently
Data Source
AI summary
In a display device, the anode voltage of an organic light emitting element is periodically reset. The control terminal of a driving transistor is periodically reset, and an input data voltage is connected to the control terminal through an input terminal and an output terminal of the driving transistor. As a result, good control over the displayed luminance is achieved. Other features are also provided.