Display Driving Control for Variable-Frame Luminance Stability
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Solution Overview
Problem
Display devices operating in variable frame mode experience luminance issues due to transistor leakage and hysteresis characteristics, leading to luminance decreases at low frequencies and increases at high frequencies, caused by frequency discordance between rendering and driving frequencies.
Innovation Solution
A driving controller that includes an on-duty determiner, first and second compensation value determiners, and a comparator to adjust bias voltage compensation values based on frame cycle variations and frequency changes, ensuring the sum of compensation values does not exceed power supply limits, thereby stabilizing luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable frame mode is used to synchronize rendering frequency with driving frequency, then tearing phenomenon is prevented, but luminance decreases at low frequencies due to transistor leakage characteristic
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the on-duty period of emission signals based on the driving frequency. At lower frequencies, the on-duty period is extended to compensate for transistor leakage characteristics, thereby maintaining luminance while preserving the variable frame mode's tearing prevention capability
Solution Approach 2:
The patent implements feedback by using a lookup table that stores pre-calculated on-duty period values corresponding to different driving frequencies. The system retrieves the appropriate on-duty period based on the current driving frequency, creating a closed-loop control mechanism that maintains luminance stability across frequency variations
2Reliability
If variable frame mode is used to synchronize rendering frequency with driving frequency, then tearing phenomenon is prevented, but luminance increases due to hysteresis characteristic of transistor
Solution Approach 1:
The patent applies parameter changes by adjusting the on-duty period based on driving frequency variations. This dynamic adjustment compensates for hysteresis characteristics by extending the on-duty period at lower frequencies, thereby counteracting luminance increases while maintaining the benefits of variable frame mode
3Illumination intensity
If on-duty period is extended to compensate for leakage characteristic, then luminance is maintained at low frequency, but device complexity increases due to additional compensation mechanisms
Solution Approach 1:
The patent applies copying by using a lookup table that stores pre-calculated on-duty period values for different driving frequencies. Instead of implementing complex real-time calculations, the system copies pre-determined values from the lookup table, significantly reducing computational complexity while maintaining luminance stability
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing on-duty period values in a lookup table during system initialization or calibration. This allows the system to quickly retrieve appropriate values during operation without performing complex calculations in real-time, thereby reducing device complexity
Data Source
AI summary
A display device includes an on-duty determiner which determines an on-duty period of an emission signal, based on a number of at least one cycle of a current frame, a first compensation value determiner which determines a first compensation value of a bias voltage according to a variation of the on-duty period, a second compensation value determiner which determines a second compensation value of the bias voltage, based on a driving frequency of a previous frame, and a third compensation value determiner which determines a third compensation value, based on the first compensation value and the second compensation value.