Display Device Scan Driver Bias Control for Flicker Reduction
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Solution Overview
Problem
Display devices face issues with image quality due to current leakage and flicker at low driving frequencies, and image distortion caused by changes in frame frequency and response speed, particularly when displaying images at various frame frequencies.
Innovation Solution
A display device with a pixel structure that includes multiple transistors and a timing controller to control the bias state of the driving transistor, using specific scan signals and emission control signals to manage the on-bias state of the transistors, ensuring stable luminance and minimizing flicker by controlling the timing of voltage supply and transistor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the driving frequency is lowered to reduce power consumption, then power consumption is reduced, but current leakage occurs and image flicker is recognized
Solution Approach 1:
The patent applies periodic action by supplying scan signals multiple times during the non-emission period at a frequency higher than the frame frequency. This periodic scanning maintains the on-bias state of the driving transistor, preventing current leakage and flicker even when the overall frame frequency is reduced for low power consumption operation.
Solution Approach 2:
The patent implements preliminary action by establishing the on-bias state of the driving transistor through repeated scan signal supply during the non-emission period before the actual emission period begins. This preliminary biasing ensures stable transistor operation and prevents luminance instability during the subsequent emission period.
2Adaptability or versatility
If the frame frequency is changed to display images in various conditions, then adaptability is improved, but image distortion occurs due to change in frame response speed
Solution Approach 1:
The patent applies dynamics by making the scan signal supply frequency adjustable based on the frame frequency. The emission driver dynamically adapts the scanning rate to match different frame frequencies while maintaining the on-bias state, allowing the display to operate stably across various frame frequencies without image distortion.
Solution Approach 2:
The patent implements parameter changes by adjusting the frequency of scan signal supply according to the frame frequency. The emission driver changes the scanning parameters dynamically, ensuring that the driving transistor maintains proper bias state across different operating conditions while preserving image stability.
3Stability of the object's composition
If multiple scan signals are supplied to control transistor bias state, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the emission driver to perform multiple functions: it generates scan signals, controls the timing of voltage supply to nodes, manages transistor bias states, and adapts to different frame frequencies. This multi-functional approach achieves luminance uniformity without requiring separate dedicated circuits for each function.
Data Source
AI summary
A display device includes a pixel including a first transistor coupled between a first node and a second node, an emission driver supplying an emission control signal at a first frequency to an emission control line, a scan driver supplying first to fourth scan signals respectively to first to fourth scan lines, a data driver supplying a data signal to a data line, and a timing controller. The first scan signal controls a timing at which a voltage of a first power source is supplied to the first node or the second node, and the second scan signal controls a timing at which a first electrode of the first transistor and a gate electrode of the first transistor are coupled to each other. The scan driver controls a bias state of the first transistor by supplying, plural times, the first and second scan signals in a non-emission period.