Display Device Flicker Reduction via Balancing Voltage
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Solution Overview
Problem
Flicker occurs in liquid crystal display (LCD) devices due to refresh rate variation, caused by changes in the vertical blank interval affecting current leakage time and voltage levels in sub-pixels, leading to varying brightness and flicker.
Innovation Solution
A driving method and display device configuration that includes a processor to determine the vertical blank interval and activate data lines with balancing voltages related to the last frame's data, reducing voltage differences and leakage currents during vertical blank intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the vertical blank interval is changed for refresh rate variation, then the refresh rate adaptability is improved, but the brightness stability deteriorates due to varying current leakage time causing flicker
Solution Approach 1:
The patent applies preliminary action by transmitting balancing voltage data during the vertical blank interval before the next frame data period. This allows the liquid crystal capacitors to be pre-adjusted to appropriate voltage levels before the actual display frame begins, compensating for the variable leakage current effects that will occur during the upcoming vertical blank interval. The balancing voltage is calculated based on the refresh rate and transmitted in advance, ensuring brightness stability without affecting the displayed image content.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the voltage level applied to liquid crystal capacitors during the vertical blank interval based on the refresh rate. Different refresh rates (e.g., 60Hz, 120Hz, 144Hz) correspond to different vertical blank interval durations, and the patent modifies the balancing voltage parameter accordingly. This dynamic parameter adjustment compensates for the varying current leakage effects caused by different interval lengths, maintaining consistent brightness across different refresh rates.
2Adaptability or versatility
If the vertical blank interval duration varies with refresh rate, then the refresh rate flexibility is improved, but the voltage level consistency deteriorates due to different leakage current losses
Solution Approach 1:
The patent employs feedback by calculating the required balancing voltage based on the actual refresh rate and vertical blank interval duration. The system monitors the refresh rate parameter and uses this information to determine the appropriate compensation voltage needed. This feedback mechanism ensures that the voltage level consistency is maintained by continuously adapting the balancing voltage to match the current operating conditions, compensating for the variable leakage current effects.
Solution Approach 2:
The balancing voltage is calculated and transmitted in advance during the vertical blank interval, before the next frame data period begins. This preliminary action allows the liquid crystal capacitors to be pre-adjusted to the correct voltage level, ensuring that when the actual display frame is shown, the voltage levels are consistent and flicker-free. The compensation is performed proactively rather than reactively.
3Illumination intensity
If balancing voltage is applied during vertical blank interval, then the flicker is reduced, but the data line activation complexity increases
Solution Approach 1:
The patent applies universality by using the existing data line infrastructure for dual purposes: transmitting both normal display frame data and balancing voltage data. The same data lines that carry image information during the frame data period are reused to transmit balancing voltage information during the vertical blank interval. This multi-functionality approach avoids the need for separate dedicated lines for balancing voltage, thereby reducing the increase in device complexity while still achieving flicker reduction.
Solution Approach 2:
The patent implements periodic action by utilizing the periodic nature of the vertical blank interval that naturally occurs with each refresh cycle. The balancing voltage transmission is synchronized with this periodic structure, occurring only during the vertical blank intervals when no frame data is being transmitted. This approach leverages the existing periodic timing structure of the display refresh, avoiding the need for additional continuous activation circuits and reducing overall system complexity.
Data Source
AI summary
A driving method of display device for a display device capable of reducing flicker due to refresh rate variation includes: determining whether a processor of the display device is generating a vertical blank interval of an image signal, wherein said vertical blank interval is next to a last frame data period thereof, and the last frame data period is for a last frame to be displayed by a display panel; and activating a data line of the display panel with a balancing voltage related to data of a line of the last frame when the processor is generating the vertical blank interval, wherein a plurality of sub-pixels of the display panel connects to the data line, the data of the line of the last frame are sequentially transmitted to the plurality of sub-pixels in the last frame data period for displaying the last frame. Said display device is also disclosed.