Gate Driver Circuit PWM Emission Signals Flicker Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
OLED display devices experience reduced luminance and flicker issues during low-frequency driving due to off-currents, leading to non-uniform luminance and visible flicker, especially when power consumption is reduced.
Innovation Solution
A gate driver circuit and driving method that outputs PWM emission signals with varying pulse widths and delay times to control the luminance of OLEDs, ensuring uniformity and reducing frequency components that cause flicker, by gradually decreasing the off-period of emission signals during low-frequency driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If display driving frequency is reduced to lower power consumption, then power consumption is decreased, but luminance uniformity deteriorates and flicker becomes visible
Solution Approach 1:
The emission signal period is divided into multiple sub-periods, each with different pulse widths. This segmentation allows the light-emitting transistor to be turned on and off multiple times within one frame period, maintaining luminance uniformity while operating at low driving frequency. The gate driver circuit outputs multiple emission signals with varying pulse widths to compensate for off-current effects.
Solution Approach 2:
The patent dynamically adjusts the pulse width of emission signals based on the sub-period timing. By making the pulse width variable rather than fixed, the system can adapt to different phases of the emission period to maintain uniform luminance. The pulse width is extended in later sub-periods to compensate for cumulative off-current effects.
2Loss of energy
If display driving frequency is reduced to lower power consumption, then power consumption is decreased, but flicker becomes visible
Solution Approach 1:
The emission signal is segmented into multiple sub-periods with different pulse widths, which distributes the emission duty cycle across multiple intervals. This prevents the formation of prominent low-frequency flicker components that would occur with a single long emission pulse at low driving frequency.
Solution Approach 2:
The patent employs periodic emission signals with varying pulse widths within each frame period. By using multiple periodic emission cycles rather than a single long pulse, the system maintains higher effective emission frequency components that are less perceptible as flicker, while still operating at reduced overall driving frequency.
3Illumination intensity
If emission signal pulse width is extended to maintain luminance, then luminance is maintained, but off-current effects increase
Solution Approach 1:
Instead of using a single long emission pulse, the total emission duty cycle is segmented into multiple shorter pulses with different pulse widths. This reduces the cumulative off-current effect while maintaining the integrated luminance output, as each shorter pulse has less time for off-current to accumulate compared to a single long pulse.
Solution Approach 2:
Different sub-periods use different pulse widths tailored to their specific timing within the frame period. Later sub-periods use longer pulse widths to compensate for off-current accumulation, while earlier sub-periods use shorter pulse widths. This localized optimization of pulse width for each sub-period maintains overall luminance while managing off-current effects.
Data Source
AI summary
A gate driver circuit, a display panel, and a display device. A number of emission start signals, with at least one a delay time, a pulse width, or a combination thereof, are supplied in a frame period in which display driving is performed at a low driving frequency. This decreases a degree by which luminance appearing in the frame period is reduced, or changes characteristics of frequency components of luminance, thereby preventing flicker from being observed. The display driving is performed at the low driving frequency reduces power consumption, and is performed at a lower driving frequency to improve the efficiency of the display device.