AM-OLED Pixel Voltage Compensation via Driver Extraction
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Solution Overview
Problem
In active matrix organic light emitting diode (AM-OLED) displays, manufacturing variations can result in different threshold voltages for driving transistors, leading to inconsistent brightness across pixels when receiving the same image signal, and conventional solutions increase costs and reduce aperture ratio.
Innovation Solution
A display device with a driving module that updates voltage stored in each pixel during a frame period, comprising programming and emission periods, to ensure consistent brightness across pixels without flicker, using a scan driver, data driver, and control signals to manage pixel activation and deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional method of using six transistors and a capacitor per pixel is used to compensate for threshold voltage variations, then brightness consistency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the threshold voltage compensation function from the pixel-level circuitry and relocates it to the driver circuitry. Specifically, the data driver performs voltage compensation for each pixel based on its threshold voltage characteristics, eliminating the need for six-transistor compensation circuits within each pixel. This extraction principle reduces pixel complexity while maintaining brightness consistency.
Solution Approach 2:
The patent introduces an intermediary compensation mechanism in the data driver that mediates between the image signal and the pixel driving voltage. The data driver acts as an intermediary that adjusts the driving voltage based on threshold voltage measurements, thereby compensating for variations without requiring complex pixel circuits. This intermediary approach resolves the contradiction by handling compensation externally.
2Manufacturing precision
If six transistors and a capacitor are used per pixel for threshold voltage compensation, then brightness uniformity is improved, but aperture ratio decreases
Solution Approach 1:
The patent extracts the compensation functionality from the pixel area and places it in the driver circuitry. By removing the six-transistor compensation circuit from the pixel, the aperture ratio is significantly improved as the pixel can be designed with fewer components occupying less area, while the compensation function is preserved in the data driver.
Solution Approach 2:
The patent moves the compensation function from the two-dimensional pixel plane to the driver circuit dimension. Instead of compensating within the pixel area, the compensation is performed in the driver circuit domain, effectively relocating the solution to a different spatial dimension where it does not consume pixel aperture area.
3Manufacturing precision
If six transistors and a capacitor are used per pixel for threshold voltage compensation, then brightness consistency is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the compensation function from the pixel and implements it in the data driver, reducing the number of transistors and capacitors that need to be manufactured and assembled in each pixel. This extraction directly reduces manufacturing complexity and cost while maintaining brightness consistency through driver-based compensation.
Solution Approach 2:
The data driver is designed to perform multiple functions: driving the pixels and simultaneously performing threshold voltage compensation. This multi-functionality eliminates the need for separate compensation circuits in each pixel, reducing overall component count and manufacturing cost while maintaining brightness consistency.
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 ensures consistent brightness across pixels, preventing flicker and allowing for correct image display even with varying threshold voltages, while maintaining a high aperture ratio and reducing costs.
Implementation Method 1
The luminescence element is lighted according to a driving current generated by the driving transistor
Data Source
AI summary
A display device including a plurality of pixels and a driving module is disclosed. Each pixel stores voltage and displays brightness according to the stored voltage. The driving module updates the stored voltage during a frame period. The frame period includes a plurality of row times. Each row time includes at least one programming period and at least one emission period. The driving module de-activates the pixels to stop displaying brightness during the programming periods and activates the pixels to display brightness during the emission periods.