Bias Voltage Control for Display Flicker Reduction
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Solution Overview
Problem
Display devices experience image quality degradation due to flicker when operating at low-speed driving frequencies, particularly due to grayscale variations, which affects the quality of displayed images.
Innovation Solution
A display device and method that adjust the bias voltage level based on the grayscale of the image, specifically by dividing the display panel into blocks and controlling the bias voltage differently in refresh and skip frames to maintain image quality at low-speed frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the display device operates at a low-speed driving frequency, then power consumption is reduced, but image quality deteriorates due to flicker caused by grayscale variations
Solution Approach 1:
The patent applies dynamics by making the bias voltage adjustable and variable rather than fixed. The bias voltage level is dynamically changed based on the grayscale value of image data, allowing the system to adapt to different operating conditions and maintain image quality across various driving frequencies including low-speed modes
Solution Approach 2:
The patent changes the parameter of bias voltage level to resolve the contradiction. By varying the bias voltage applied to the driving transistor according to grayscale values (e.g., higher bias for darker regions, lower bias for brighter regions), the system maintains stable transistor operation and reduces flicker while operating at low driving frequencies
2Device complexity
If a fixed bias voltage is applied to the driving transistor, then the circuit design is simple, but image quality deteriorates due to flicker at low driving frequencies
Solution Approach 1:
The patent transitions from a static fixed bias voltage design to a dynamic adjustable bias voltage system. The bias voltage is now controlled based on grayscale values, requiring additional control logic but significantly improving image quality by preventing flicker at low driving frequencies
Solution Approach 2:
The patent implements feedback by using the grayscale value of image data as input to determine the appropriate bias voltage level. This feedback mechanism allows the system to automatically adjust the bias voltage based on the actual image content being displayed, maintaining optimal transistor operation across different grayscale conditions
Data Source
AI summary
A display device can include a light-emitting element, a driving transistor providing a driving current to the light-emitting element using a driving voltage, and a plurality of switching transistors controlling driving of the driving transistor are disposed on a display panel. A gate driving circuit supplies scan signals to the display panel through gate lines. An emission driving circuit supplies a plurality of emission signals to the display panel through a plurality of emission signal lines. A data driving circuit supplies a data voltage to the display panel. A timing controller divides the display panel into a plurality of blocks and controls a level of a bias voltage applied to the driving transistor of a corresponding block among the plurality of blocks according to a grayscale of the data voltage supplied to the corresponding block in a low-speed mode operating at a low-speed driving frequency.